CN111213325A - Method for reporting channel state information in wireless communication system and apparatus therefor - Google Patents

Abstract

The present specification provides a method of reporting Channel State Information (CSI) in a wireless communication system and an apparatus thereof. Specifically, a method of a terminal reporting Channel State Information (CSI) in a wireless communication system may include the steps of: measuring a CSI reference signal (CSI-RS) transmitted through a multi-panel from a base station; and reporting the CSI generated based on the CSI-RS measurement to the base station. If the terminal receives a configuration of a CSI report not including a matrix index for phase alignment between panels from the base station, the CSI includes only a first matrix index for Wideband (WB) panel compensation and a second matrix index for Subband (SB) panel compensation, and the CSI may be calculated by the first matrix index, the second matrix index, and a specific matrix index associated with phase alignment between panels.

Description

Method for reporting channel state information in wireless communication system and apparatus therefor

Technical Field

The present disclosure relates to a wireless communication system, and more particularly, to a method of reporting channel state information by a user equipment and an apparatus supporting the same.

Background

In general, mobile communication systems have been developed to provide voice services while guaranteeing user mobility. These mobile communication systems have gradually expanded their coverage range from voice services through data services to high-speed data services. However, as current mobile communication systems suffer from resource shortages and users demand even higher-speed services, development of more advanced mobile communication systems is required.

Requirements of the next generation mobile communication system may include support of huge data services, a significant increase in the transfer rate of each user, a significant increase in the number of accommodated connection devices, very low end-to-end delay, and high energy efficiency. To this end, various technologies such as small cell enhancement, dual connectivity, massive Multiple Input Multiple Output (MIMO), in-band full duplex, non-orthogonal multiple access (NOMA), support for ultra-wideband, and device networking have been studied.

Disclosure of Invention

Technical problem

The present disclosure proposes a method of transmitting and receiving Channel State Information (CSI) in a wireless communication system.

Furthermore, the present disclosure proposes various reporting settings for CSI reporting/feedback. In particular, the present disclosure proposes a new codebook and/or new reporting/feedback configuration (or information) for supporting beamforming in a new rat (nr) system with newly introduced multiple panels.

The technical objects of the present disclosure are not limited to the above technical objects, and other technical objects not described above may be obviously understood by those skilled in the art to which the present disclosure pertains from the following description.

Technical scheme

In a method of reporting Channel State Information (CSI) by a user equipment in a wireless communication system according to an embodiment of the present disclosure, the method may include measuring a CSI-Reference Signal (RS) transmitted through a multi-panel from a base station, and reporting the CSI generated based on the CSI-RS measurement to the base station. If a CSI report not including a matrix index for phase alignment between panels is configured for a user equipment from a base station, the CSI may include only a first matrix index for Wideband (WB) panel compensation and a second matrix index for Subband (SB) panel compensation, and may be calculated using the first matrix index, the second matrix index, and a specific matrix index related to phase alignment between panels.

Further, in a method according to an embodiment of the present disclosure, the first matrix index and the second matrix index may be included in a Precoding Matrix Indicator (PMI) within the CSI and reported. In this case, the result of calculation using the first matrix index, the second matrix index, and a specific matrix index related to phase alignment between panels may be included in a Channel Quality Indicator (CQI) within CSI and reported.

In this case, the specific matrix index may be indicated by the base station through higher layer signaling.

Alternatively, the specific matrix index may belong to a matrix index set configured by the base station through higher layer signaling.

Alternatively, the specific matrix index may correspond to a lowest matrix index among matrix indexes pre-configured with respect to phase alignment between panels.

Alternatively, the specific matrix index may correspond to all matrix indexes that are pre-configured with respect to phase alignment between panels.

Alternatively, the specific matrix index may correspond to a matrix index randomly selected by the user equipment among matrix indexes related to phase alignment between panels.

Further, in the method according to an embodiment of the present disclosure, CSI-RS measurement may be performed on at least one CSI-RS resource selected by the user equipment among CSI-RS resources configured by the base station. In this case, the CSI may further include an index of the at least one CSI-RS resource.

In a user equipment reporting Channel State Information (CSI) in a wireless communication system according to an embodiment of the present disclosure, the user equipment includes a Radio Frequency (RF) unit for transmitting and receiving a wireless signal and a processor controlling the RF unit. The processor may be configured to measure a CSI-Reference Signal (RS) transmitted through the multi-panel from the base station and report CSI generated based on the CSI-RS measurement to the base station. If a CSI report not including a matrix index for phase alignment between panels can be configured for a user equipment from a base station, the CSI may include only a first matrix index for Wideband (WB) panel compensation and a second matrix index for Subband (SB) panel compensation, and the CSI may be calculated using the first matrix index, the second matrix index, and a specific matrix index related to phase alignment between panels.

Further, in the user equipment according to an embodiment of the present disclosure, the first matrix index and the second matrix index may be included in a Precoding Matrix Indicator (PMI) within the CSI and reported. In this case, the result of calculation using the first matrix index, the second matrix index, and a specific matrix index related to phase alignment between panels may be included in a Channel Quality Indicator (CQI) within CSI and reported.

Advantageous effects

According to the embodiments of the present disclosure, there is an effect that: since the amount of feedback information to be reported by the UE may be reduced, the complexity and/or overhead of CSI reporting (or feedback) by the UE may be reduced.

Further, according to the embodiment of the present disclosure, there is an effect that: since CSI-RS measurements or CSI calculations and reporting may be performed on only some resources configured or indicated in the UE, the complexity and/or overhead of CSI reporting for the UE may be reduced.

Effects of the present disclosure are not limited to the above-described effects, and other technical effects not described above may be obviously understood by those skilled in the art to which the present disclosure pertains from the following description.

Drawings

The accompanying drawings, which are included to provide a part of the specification and an understanding of the present disclosure and provide a description of the embodiments of the disclosure and together with the description below describe features of the disclosure.

Fig. 1 shows an example of the overall structure of a New Radio (NR) system in which the method proposed by the present disclosure can be implemented.

Fig. 2 illustrates a relationship between an Uplink (UL) frame and a Downlink (DL) frame in a wireless communication system in which the method proposed by the present disclosure can be implemented.

Fig. 3 illustrates an example of a resource grid supported in a wireless communication system in which the method proposed by the present disclosure can be implemented.

Fig. 4 shows an example of a resource grid for various antenna ports and parameter sets to which the methods presented in this disclosure may be applied.

Fig. 5 is a diagram illustrating one example of a self-contained slot structure to which the method proposed in this specification can be applied.

Fig. 6 shows an example of a connection scheme of a TXRU and an antenna element to which the method proposed in the present disclosure can be applied.

Fig. 7 illustrates various examples of service areas of a TXRU to which the methods presented in this disclosure may be applied.

Fig. 8 illustrates an example of a MIMO system using a 2D planar array structure to which the method proposed in the present disclosure can be applied.

Fig. 9 shows an example of a CSI framework considered in an NR system to which the method proposed in the present disclosure can be applied.

Fig. 10 shows an example of a multi-antenna structure to which the method proposed by the present disclosure can be applied.

Fig. 11 shows an example of a plurality of antenna panel arrays to which the method proposed by the present disclosure can be applied.

Fig. 12 illustrates an example of an operation flowchart of a UE reporting Channel State Information (CSI) in a wireless communication system to which the method proposed by the present disclosure can be applied.

Fig. 13 shows a block diagram of a wireless communication device according to an embodiment of the present disclosure.

Fig. 14 shows a block diagram of a communication device according to an embodiment of the present disclosure.

Detailed Description

Some embodiments of the present disclosure are described in detail with reference to the accompanying drawings. The detailed description, which is to be disclosed in connection with the appended drawings, is intended to describe some exemplary embodiments of the present disclosure, and is not intended to describe the only embodiments of the present disclosure. The following detailed description includes further details in order to provide a thorough understanding of the present disclosure. However, it will be understood by those skilled in the art that the present disclosure may be practiced without these further details.

In some cases, in order to avoid obscuring the concepts of the present disclosure, known structures and devices are omitted or may be shown in block diagram form based on the core functions of the respective structures and devices.

In the present disclosure, a base station has the meaning of a terminal node of a network that directly communicates with a terminal. In this document, a specific operation described as being performed by the base station may be performed by an upper node of the base station in some cases. That is, it is apparent that various operations performed for communication with a terminal in a network constituted by a plurality of network nodes including a base station may be performed by the base station or network nodes other than the base station. A "Base Station (BS)" may be replaced by a term including a fixed station, a node B, an evolved node B (enb), a Base Transceiver System (BTS), an Access Point (AP), a next generation NB, a general NB, a gnnodeb (gNB), and the like. Also, a "terminal" may be fixed or mobile, and may be replaced by terms including a mobile station (UE), a Mobile Station (MS), a User Terminal (UT), a mobile subscriber station (MSs), a Subscriber Station (SS), an Advanced Mobile Station (AMS), a Wireless Terminal (WT), a Machine Type Communication (MTC) device, a machine-to-machine (M2M) device, a device-to-device (D2D) device, and the like.

Hereinafter, Downlink (DL) means communication from a base station to a UE, and Uplink (UL) means communication from a UE to a base station. In DL, a transmitter may be a part of a base station and a receiver may be a part of a UE. In the UL, the transmitter may be part of the UE and the receiver may be part of the base station.

Specific terms used in the following description are provided to aid in understanding the present disclosure, and the use of these specific terms may be changed in various forms without departing from the technical spirit of the present disclosure.

The following techniques may be used in various wireless communication systems such as Code Division Multiple Access (CDMA), Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA), Orthogonal Frequency Division Multiple Access (OFDMA), single carrier frequency division multiple access (SC-FDMA), and non-orthogonal multiple access (NOMA). CDMA may be implemented using radio technologies such as Universal Terrestrial Radio Access (UTRA) or CDMA 2000. TDMA may be implemented using radio technologies such as global system for mobile communications (GSM)/General Packet Radio Service (GPRS)/enhanced data rates for GSM evolution (EDGE). OFDMA may be implemented using radio technologies such as Institute of Electrical and Electronics Engineers (IEEE)802.11(Wi-Fi), IEEE802.16(WiMAX), IEEE 802-20, or evolved UTRA (E-UTRA). UTRA is part of the Universal Mobile Telecommunications System (UMTS). The 3 rd generation partnership project (3GPP) Long Term Evolution (LTE) is part of an evolved UMTS (E-UMTS) using evolved UMTS terrestrial radio access (E-UTRA) that employs OFDMA in the downlink and SC-FDMA in the uplink. LTE-advanced (LTE-A) is an evolution of 3GPP LTE.

Embodiments of the present disclosure may be supported by standard documents disclosed in at least one of IEEE802, 3GPP, and 3GPP2 (i.e., radio access systems). That is, steps or portions which belong to embodiments of the present disclosure and are not described in order to clearly disclose the technical spirit of the present disclosure may be supported by these documents. In addition, all terms disclosed in this document can be described by these standard documents.

For clarity of description, 3GPP LTE/LTE-a/new rat (nr) is mainly described, but the technical features of the present disclosure are not limited thereto.

Definition of terms

eLTE eNB: an eLTE eNB is an evolution of an eNB that supports connections to EPCs and NGCs.

And g NB: except for the nodes supporting the NR in addition to the connection with the NGC.

The new RAN: a radio access network supporting NR or E-UTRA or interworking with NGC.

Network slicing: a network slice is a network defined by an operator to provide a solution optimized for a specific market scenario that requires specific requirements with inter-terminal scope.

Network function: a network function is a logical node in the network infrastructure with well-defined external interfaces and well-defined functional operations.

NG-C: a control plane interface for the NG2 reference point between the new RAN and the NGC.

NG-U: a user plane interface for the NG3 reference point between the new RAN and the NGC.

Non-independent NR: the gbb requires deployment configurations of LTE enbs as anchors for control plane connections to the EPC or ehte enbs as anchors for control plane connections to the NGC.

Non-independent E-UTRA: the lte eNB requires a deployment configuration of the gNB as an anchor for control plane connections to the NGC.

A user plane gateway: and the terminal point of the NG-U interface.

Overview of the System

Fig. 1 is a diagram showing an example of an overall structure of a New Radio (NR) system in which the method proposed by the present disclosure can be implemented.

Referring to fig. 1, the NG-RAN is composed of a gNB providing an NG-RA user plane (new AS sublayer/PDCP/RLC/MAC/PHY) and a control plane (RRC) protocol terminal for a UE (user equipment).

The gnbs are connected to each other via an Xn interface.

The gNB is also connected to the NGC via the NG interface.

More specifically, the gNB is connected to an access and mobility management function (AMF) via an N2 interface and to a User Plane Function (UPF) via an N3 interface.

New Rat (NR) parameter set and frame structure

In NR systems, multiple parameter sets may be supported. The parameter set may be defined by subcarrier spacing and CP (cyclic prefix) overhead. The spacing between the multiple subcarriers may be derived by scaling the basic subcarrier spacing to an integer N (or μ). In addition, although it is assumed that very low subcarrier spacing is not used at very high subcarrier frequencies, the parameter set to be used may be selected independently of the frequency band.

In addition, in the NR system, various frame structures according to a plurality of parameter sets may be supported.

Hereinafter, an Orthogonal Frequency Division Multiplexing (OFDM) parameter set and a frame structure that can be considered in the NR system will be described.

The plurality of OFDM parameter sets supported in the NR system may be as defined in table 1.

[ Table 1]

μ	Δf＝2μ·15[kHz]	Cyclic prefix
			0	15	Is normal
1	30	Is normal
			2	60	Normal, extended
3	120	Is normal
			4	240	Is normal
5	480	Is normal

In an embodiment of the present disclosure, "Downlink (DL)" refers to communication from the eNB to the UE, and "Uplink (UL)" refers to communication from the UE to the eNB. In the downlink, the transmitter may be part of an eNB and the receiver may be part of a UE. In the uplink, the transmitter may be part of the UE and the receiver may be part of the eNB. Regarding the frame structure in the NR system, the sizes of various fields in the time domain are represented as time units T_s＝1/(Δf_max·N_f) Multiples of (a). In this case,. DELTA.f_max＝480·10³And N is_f4096. DL and UL transmissions are configured with T_f＝(Δf_maxN_f/100)·T_sA radio frame of a sector of 10 ms. A radio frame consists of ten subframes, each subframe having a T_sf＝(Δf_maxN_f/1000)·T_s1ms segment. In this case, there may be a set of UL frames and a set of DL frames.

Fig. 2 illustrates a relationship between an UL frame and a DL frame in a wireless communication system in which the method proposed by the present disclosure can be implemented.

As shown in FIG. 2, the UL frame number I from a User Equipment (UE) needs to be T before the corresponding DL frame in the UE starts_TA＝N_TAT_sAnd (5) sending.

With respect to parameter set μ, the slots are in accordance with in a subframe

In ascending order, in radio frames

The ascending order of (1). A time slot is formed by

Is formed of successive OFDM symbols, and

determined according to the parameter set and time slot configuration used. Time slots in subframes

Is temporally identical to an OFDM symbol in the same subframe

Is aligned.

Not all UEs are capable of transmitting and receiving simultaneously, which means that not all OFDM symbols in a DL slot or UL slot are available.

Table 2 shows the number of OFDM symbols per slot of the normal CP in the parameter set μ, and table 3 shows the number of OFDM symbols per slot of the extended CP in the parameter set μ.

[ Table 2]

[ Table 3]

NR physical resource

Regarding physical resources in the NR system, antenna ports, resource grid, resource elements, resource blocks, carrier parts, etc. may be considered.

Hereinafter, the above-described physical resources that may be considered in the NR system will be described in more detail.

First, with respect to antenna ports, an antenna port is defined such that a channel transmitting a symbol on one antenna port can be inferred from another channel transmitting a symbol on the same antenna port. When the large-scale nature of a channel transmitting symbols on one antenna port can be inferred from another channel transmitting symbols on another antenna port, the two antenna ports can be in a QC/QCL (quasi co-located or quasi co-located) relationship. Herein, the large-scale property may include at least one of a delay spread, a doppler shift, an average gain, and an average delay.

Fig. 3 illustrates an example of a resource grid supported in a wireless communication system in which the method proposed by the present disclosure can be implemented.

Referring to fig. 3, the resource grid consists of in the frequency domain

Sub-carriers, and each subframe consists of 14 · 2 μ OFDM symbols, but the disclosure is not limited thereto.

In NR systems, the transmitted signal is described by one or more resource grids, which are defined by

Sub-carriers and 2^μ

One OFDM symbol. In the present context, it is intended that,

as described above

The maximum transmission bandwidth is indicated and may vary not only between parameter sets but also between UL and DL.

In this case, one resource grid may be configured for the parameter set μ and the antenna port p, as shown in fig. 4.

Fig. 4 shows an example of an antenna port and parameter set specific resource grid to which the methods presented herein may be applied.

The individual elements of the resource grid for parameter set μ and antenna port p are indicated as resource elements and may be represented by index pairs

Is uniquely identified. In the present context, it is intended that,

is an index in the frequency domain, and

indicating the location of the symbols in the subframe. To indicate resource elements in a slot, index pairs are used

In the present context, it is intended that,

resource elements for parameter set mu and antenna port p

Corresponding to complex values

When there is no risk of confusion or when a particular antenna port or parameter set is specified, the indices p and μmay be discarded, so that the complex value may become a

Or

In addition, a physical resource block is defined as in the frequency domain

A number of consecutive subcarriers. In the frequency domain, the physical resource blocks may range from 0 to

And (6) numbering. At this time, the physical resource block number n_PRBThe relationship with the resource element (k, l) can be given by equation 1.

[ formula 1]

In addition, with respect to the carrier part, the UE may be configured to receive or transmit the carrier part using only a subset of the resource grid. At this time, the set of resource blocks that the UE is configured to receive or transmit is from 0 to

And (6) numbering.

Beam management

In NR, beam management is defined as follows.

Beam management: a set of L1/L2 processes for obtaining and maintaining a set of TRP and/or UE beams available for DL and UL transmission/reception, comprising at least:

-beam determination: an operation in which the TRP or the UE selects its transmission/reception beam.

-beam measurement: an operation in which the TRP or the UE selects its transmission/reception beam.

-beam reporting: the UE reports an operation of the information of the beamformed signals based on the beam measurement.

-beam sweeping: an operation of covering a spatial region with transmitted and/or received beams for a time interval according to a predetermined scheme.

In addition, the TRP and Tx/Rx beam correspondence in the UE is defined as follows:

-maintaining the Tx/Rx beam correspondence in the TRP if at least one of the following is fulfilled:

-the TRP may determine a TRP receive beam for uplink reception based on downlink measurements of the UE on one or more transmit beams of the TRP.

The TRP may determine a TRP Tx beam for downlink reception based on uplink measurements of TRP for one or more Rx beams of TRP.

-maintaining the Tx/Rx beam correspondence in the UE if at least one of the following is fulfilled:

the UE may determine a UE Tx beam for uplink transmission based on UE downlink measurements for one or more Rx beams of the UE.

The UE may determine a UE receive beam for downlink reception based on uplink measurements on one or more Tx beams based on the instructions of the TRP.

-an indication of the capability of the TRP to support UE beam correspondence related information.

The following DL L1/L2 beam management procedures are supported within one or more TRPs.

P-1: for allowing UE measurements on different TRP Tx beams to support selection of TRP Tx beam/UE Rx beam.

For beamforming in a TRP, P-1 typically includes an intra/inter TRP Tx beam sweep from a set of different beams. For beamforming in the UE, P-1 typically includes a UE Rx beam sweep from a set of different beams.

P-2: for allowing UE measurements on different TRP Tx beams to change the TRP inter/intra Tx beams.

P-3: when the UE uses beamforming, UE measurements on the same TRP Tx beam are used to change the UE Rx beam.

At least network-triggered aperiodic reporting is supported in P-1, P-2, and P-3 related operations.

UE measurements based on RS for beam management (at least CSI-RS) are made of K (total number of beams) beams, and the UE reports measurement results of N selected Tx beams. Here, N is not a particularly fixed number. Procedures based on RS for mobility purposes are not excluded. The report information includes at least the measurement quantities of the N beams (if N < K) and information indicating the N DL transmission beams. In particular, for a UE with K '> 1 non-zero power (NZP) CSI-RS resources, the UE may report an N' CRI (CSI-RS resource indicator).

The UE may be set to the following high layer parameters for beam management.

-N ≧ 1 report setting and M ≧ 1 resource setting

-setting a link between reporting settings and resource settings in agreed CSI measurement settings.

Support for CSI-RS based P-1 and P-2 with resource and reporting settings.

P-3 can be supported with or without reporting settings.

-the report setting comprises at least:

-information indicative of the selected beam

-L1 measurement report

Time domain operation (e.g. aperiodic operation, periodic operation, semi-persistent operation)

-frequency granularity when multiple frequency granularities are supported

-the resource setting comprises at least:

time domain operation (e.g. aperiodic operation, periodic operation, semi-persistent operation)

-RS type: at least NZP CSI-RS

-at least one set of CSI-RS resources. Each set of CSI-RS resources includes K ≧ 1CSI-RS resources (some parameters of the K CSI-RS resources may be the same.

Further, NR supports the next beam report considering L groups, L > 1.

-information indicating the smallest group

Measurement quantity (L1 RSRP and CSI reporting support (when CSI-RS is used for CSI acquisition)) N1 beams.

-information indicating Nl DL transmission beams, if applicable

The group-based beam reporting as described above may be configured UE-by-UE. Further, the group-based beam reporting may be turned off per UE (e.g., when L ═ 1 or Nl ═ 1).

NR supports mechanisms where the UE may trigger the UE to recover from beam failure.

A beam failure event occurs when the quality of the beam pair link of the associated control channel is sufficiently low (e.g., a timeout of an associated timer compared to a threshold). When a beam failure occurs, a mechanism to recover from the beam failure is triggered.

The network explicitly configures the resources for transmission of UL signals in the UE for recovery purposes. The configuration of resources is supported where the base station is listening from all or some directions (e.g., random access area).

The UL transmissions/resources reporting beam failure may be located at the same time instance as the PRACH (resources orthogonal to the PRACH resources) or at a different time instance than the PRACH (configurable for the UE). Transmission of DL signals is supported so that the UE may monitor the beams to identify new potential beams.

Regardless of the beam related indication, NR supports beam management. When providing the beam-related indication, information on a UE-side beamforming/receiving procedure for CSI-RS based measurement may be indicated to the UE through the QCL. As QCL parameters to be supported by NR, parameters of delay, doppler, average gain, and the like used in the LTE system and spatial parameters for beamforming at the receiver are planned to be added, and the QCL parameters may include an arrival angle-related parameter in terms of UE reception beamforming and/or an emergence angle-related parameter in terms of base station reception beamforming. NR supports the use of the same or different beams in control channel and corresponding data channel transmissions.

For NR-PDCCH transmissions that support robustness to beam pair blocking, the UE may be configured to simultaneously monitor NR-PDCCH on the M beam pair link. Here, M ≧ 1 and the maximum value of M may depend at least on the UE capability.

The UE may be configured to monitor the NR-PDCCH on different beam pair links in different NR-PDCCH OFDM symbols. Parameters related to UE Rx beam configuration for monitoring NR-PDCCH on multiple beam pair links are configured by higher layer signaling or MAC CE and/or considered in search space design.

At a minimum, NR supports an indication of spatial QCL hypothesis between DL RS antenna ports for demodulating DL control channels. Candidate signaling methods for beam indication of the NR-PDCCH (i.e., configuration methods for monitoring the NR-PDCCH) include MAC CE signaling, RRC signaling, DCI signaling, specification transparent and/or implicit methods, and combinations of these signaling methods.

To receive unicast DL data channels, the NR supports an indication of spatial QCL hypotheses between DL RS and DMRS antenna ports of the DL data channels.

The information indicating the RS antenna port is indicated via DCI (downlink grant). In addition, the information also indicates the RS antenna port with DMRS antenna port QCL. Different sets of DMRS antenna ports for DL data channels may be represented as different sets of RS antenna ports and QCLs.

Hereinafter, before describing the method proposed in the present disclosure in detail, contents directly or indirectly related to the method proposed in the present disclosure will be briefly described.

In next-generation communications including 5G, new rat (nr), and the like, as more and more communication apparatuses require a larger communication capacity, mobile broadband communications need to be enhanced as compared with existing radio access technologies.

In addition, large-scale Machine Type Communication (MTC) that provides various services by connecting many devices and objects anytime and anywhere is one of the major issues to be considered in next-generation communication.

In addition, communication system design or architecture is being discussed that considers services/UEs that are sensitive to reliability and delay.

Introduction of next generation Radio Access Technology (RAT) considering enhanced mobile broadband communication (eMBB), large-scale mtc (mtc), ultra-reliable and low-delay communication (URLLC) is currently under discussion, and in the present disclosure, for convenience, this technology is referred to as "new RAT (nr)".

Self-contained timeslot structure

To minimize the delay of data transmission in TDD systems, the fifth generation new RAT considers a self-contained slot structure as shown in fig. 5.

That is, fig. 5 is a diagram illustrating one example of a self-contained slot structure to which the method proposed in the present disclosure can be applied.

In fig. 5, a shaded area 510 indicates a downlink control area, and a black area 520 indicates an uplink control area.

The unmarked regions 530 may be used for downlink data transmission or for uplink data transmission.

Such a structure may be characterized in that DL transmission and UL transmission are sequentially performed in one slot, and DL data may be transmitted in one slot, and UL ACK/NACK may also be transmitted and received.

Such a slot may be defined as a "self-contained slot".

That is, with such a slot structure, it takes less time for the eNB to retransmit data to the UE when a data transmission error occurs, thereby minimizing a delay of final data transmission.

In such a self-contained slot structure, a time gap is required between the eNB and the UE for a transition process from a transmission mode to a reception mode or from a reception mode to a transmission mode.

For this, some OFDM symbols in the slot structure when switching from DL to UL are configured as Guard Periods (GP).

Analog beamforming

In millimeter waves (mmW), the wavelength is shortened so that a plurality of antenna elements can be mounted in the same area.

That is, a total of 64(8 × 8) antenna elements can be mounted in a 2-dimensional array at 0.5 λ (wavelength) intervals on a 4 × 4cm panel at a wavelength of 1cm in the 30GHz band.

Thus, in mmW, multiple antenna elements may be used to increase Beamforming (BF) gain to increase coverage or increase throughput.

In this case, if a transceiver unit (TXRU) is provided so that transmission power and phase can be adjusted for each antenna element, independent beamforming can be performed for each frequency resource.

However, when TXRUs are mounted on all of about 100 antenna elements, there is a problem that the effectiveness in terms of cost deteriorates.

Therefore, a method of mapping a plurality of antenna elements to one TXRU and adjusting the direction of a beam using an analog phase shifter is considered.

A disadvantage of this analog beamforming method is that frequency selective beamforming cannot be performed by forming only one beam direction in all frequency bands.

As an intermediate form of digital BF and analog BF and less than Q antenna elements, a hybrid BF (hbf) with B TXRUs may be considered.

In the HBF, although there is a difference according to the connection method of the B TXRU and the Q antenna elements, the number of directions of beams that can be simultaneously transmitted is limited to B or less.

Fig. 6 shows an example of a connection scheme of a TXRU and an antenna element to which the method proposed in the present disclosure can be applied.

Here, the TXRU virtualization model shows a relationship between an output signal of the TXRU and an output signal of the antenna element.

Fig. 6 (a) shows an example of a scheme in which TXRUs are connected to sub-arrays.

Referring to (a) of fig. 6, the antenna element is connected to only one TXRU. Unlike (a) of fig. 6, (b) of fig. 6 shows a scheme in which TXRUs are connected to all antenna elements.

That is, in the case of (b) of fig. 6, the antenna element is connected to all TXRUs.

In fig. 6, W denotes a phase vector multiplied by an analog phase shifter.

In other words, the direction of analog beamforming is determined by W. Here, the mapping of CSI-RS antenna ports to TXRUs may be 1 to 1 or 1 to many.

Reference Signal (RS) virtualization

In mmW, PDSCH may be transmitted in only one analog beam direction at a time through analog beamforming.

Therefore, the eNB transmits data to only a small number of UEs in a specific direction.

Accordingly, if necessary, the analog beam directions are differently configured for the respective antenna ports, so that data transmission can be simultaneously performed to a plurality of UEs in a plurality of analog beam directions.

Fig. 7 illustrates various examples of service areas of a TXRU to which the methods presented in this disclosure may be applied.

In fig. 7, 256 antenna elements are divided into 4 parts to form 4 sub-arrays, and a structure of connecting TXRUs to the respective sub-arrays will be described as an example.

When each sub-array is composed of a total of 64(8 × 8) antenna elements in the form of a 2-dimensional array, a specific analog beamforming can cover an area corresponding to a 15-degree horizontal angle area and a 15-degree vertical angle area.

That is, an area that the eNB should serve is divided into a plurality of areas, and the service is provided one at a time.

In the following description, it is assumed that CSI-RS antenna ports and TXRUs are 1-to-1 mapped.

Therefore, it can be interpreted that the antenna port and the TXRU have the same meaning as described below.

If all TXRUs (antenna ports, sub-arrays) have the same analog beamforming direction as shown in (a) of fig. 7, the throughput of the corresponding region can be increased by forming digital beams with higher resolution.

In addition, the throughput of the corresponding region may be increased by increasing the rank of transmission data to the corresponding region.

In addition, as shown in (b) of fig. 7, if each TXRU (antenna port, sub-array) has a different analog beamforming direction, data can be simultaneously transmitted to UEs distributed in a wider area in a Subframe (SF).

As shown in fig. 7 (b), two of the four antenna ports are used for PDSCH transmission to UE1 in region 1, and the remaining two antenna ports are used for PDSCH transmission to UE2 in region 2.

Further, (b) of fig. 7 shows an example in which the PDSCH 1 transmitted to the UE1 and the PDSCH2 transmitted to the UE2 are subjected to Space Division Multiplexing (SDM).

In contrast, as shown in fig. 7 (c), the PDSCH 1 transmitted to UE1 and the PDSCH2 transmitted to UE2 may be transmitted by Frequency Division Multiplexing (FDM).

Among a scheme of serving one area using all antenna ports and a scheme of simultaneously serving many areas by dividing antenna ports, a preferred scheme may be changed according to a rank and MCS for serving a UE to maximize cell throughput.

Further, the preference varies according to the amount of data to be transmitted to each UE.

The eNB calculates cell throughput or scheduling metrics that can be obtained when one area is served using all antenna ports, and calculates cell throughput or scheduling metrics that can be obtained when two areas are served by dividing the antenna ports.

The eNB compares the cell throughput or scheduling metrics available through the various schemes to select the final transmission scheme.

As a result, the number of antenna ports participating in PDSCH transmission changes from SF to SF.

In order for the eNB to calculate the transmission MCS of the PDSCH according to the number of antenna ports and reflect the calculated transmission MCS to the scheduling algorithm, CSI feedback from the appropriate UE is required.

In addition, in the case of a 3-dimensional multiple input multiple output (3D-MIMO) or full-dimensional Multiple Input Multiple Output (MIMO) technology, an Active Antenna System (AAS) having a 2-dimensional planar array structure may be used.

Fig. 8 illustrates an example of a MIMO system using a 2D planar array structure to which the method proposed in the present disclosure can be applied.

With a 2D planar array structure, a large number of antenna elements can be packaged within an available base station type of element, and adaptive electronics capability in 3D space can be provided.

Channel state information feedback

In most cellular systems including the conventional LTE system, the UE receives a pilot signal (e.g., a Reference Signal (RS)) for channel estimation from the base station, calculates Channel State Information (CSI), and reports the calculated value to the base station. The base station transmits a data signal (i.e., downlink data) based on the CSI information fed back by the UE. In case of the LTE system, the CSI information fed back by the UE includes Channel Quality Information (CQI), a Precoding Matrix Index (PMI), or a Rank Indicator (RI). Hereinafter, CQI feedback, PMI feedback, and RI feedback are described in detail.

First, CQI feedback is radio channel quality information provided from a UE to a base station in order to provide information of which Modulation and Coding Scheme (MCS) is to be applied when the base station transmits data. If the radio quality between the base station and the UE is high, the UE feeds back a high CQI value to the base station. The base station receiving a high CQI value through feedback transmits data by applying a relatively high modulation order and a low channel coding rate. In contrast, if the radio quality between the base station and the UE is low, the UE feeds back a low CQI value to the base station. The base station receiving a low CQI value through feedback transmits data by applying a relatively low modulation order and a high channel coding rate.

Next, PMI feedback is preferred precoding matrix information provided from the UE to the base station in order to provide information of which Multiple Input Multiple Output (MIMO) precoding scheme is to be applied if the base station has installed multiple antennas. The UE estimates a downlink MIMO channel between the base station and the UE from the pilot signal, and transmits information indicating which MIMO precoding is efficiently applied by the base station through PMI feedback. In case of the LTE system, only linear MIMO precoding that can be expressed in a matrix form is considered in PMI configuration.

In this case, the base station and the UE share a codebook configured with a plurality of precoding matrices. Each MIMO precoding matrix within the codebook has a unique index. Therefore, since the UE feeds back an index corresponding to the most preferable MIMO precoding matrix within the codebook through the PMI, it minimizes the amount of feedback information of the UE. In this case, the PMI value need not be set to substantially only one index.

For example, in the LTE system, if the number of transmission antenna ports is 8, a configuration may be performed such that the final 8 transmission (Tx) MIMO precoding matrices may be derived only when two indexes (e.g., W1 and W2) are combined. W1 corresponding to the first PMI is fed back at a longer period (e.g., long term) and may be referred to as a wideband PMI due to having a wideband property. Generally, W1. Further, W1 corresponding to the second PMI is fed back at a shorter period (e.g., short term) and may be referred to as a subband PMI due to having a subband property.

In this case, the final precoder may be configured with the product of W1 and W2. In this case, W1 may be configured to select a beam group for each polarization in a cross-polarized antenna environment, and W2 may be configured for the same phase between the final beam selection in each polarization and the cross polarization. The number of beams belonging to a beam group may be one. In this case, W2 may be configured for only the same phase. The number of beams belonging to a beam group and which beam group to select based on which mode of vertical beam and horizontal beam index combination can be specified by the base station through codebook configuration parameters.

Next, RI feedback is information of the number of preferred transport layers provided from the UE to the base station in order to provide information of the number of preferred transport layers by the UE if the base station and the UE install multiple antennas and are capable of multi-layer transmission through spatial multiplexing. In this case, RI has a close relationship with PMI. The reason for this is that the base station needs to know which precoding must be applied to each layer based on the number of transmission layers.

In the PMI/RI feedback configuration, a method of configuring a PMI codebook based on single-layer transmission, defining PMIs of respective layers, and feeding back PMIs by a UE may be considered. However, this method has a disadvantage in that the amount of information fed back by the PMI/RI greatly increases according to the increase in the number of transmission layers. Therefore, in the case of the LTE system, PMI codebooks according to respective numbers of transport layers have been defined. That is, for R-layer transmission, N matrices of size Nt × R are defined in the codebook. In this case, R means the number of layers, Nt means the number of Tx antenna ports, and N means the size of a codebook. Therefore, in the case of the LTE system, the size of the PMI codebook is defined regardless of the number of transport layers. In this case, the number (R) of transmission layers is the same as the rank value of the precoding matrix (Nt × R matrix).

Furthermore, in full-dimensional (FD) -MIMO for LTE systems, class a operation based on non-precoded CSI-RS and class B operation based on beamformed CSI-RS have been defined. In this case, the biggest characteristic of the class a operation is that the PMI codebook designed to support horizontal beamforming has been extended to support vertical and horizontal beamforming. Unlike the existing operation and the class a operation, the class B operation is characterized in that the base station performs transmission (e.g., transmission using a method similar to DMRS) by applying beamforming at the time of CSI-RS transmission.

For example, a 4-port CSI-RS resource a and a 4-port CSI-RS resource B may be configured such that differently oriented beamforming is applied to and transmits resources a and B in a resource unit. In this case, the UE may select a resource having excellent quality among the two CSI-RS resources, and may feed back channel state information (e.g., PMI, CQI, RI) of the corresponding resource. The index related to such CSI-RS resource selection may be referred to as CSI-RS resource indicator (CRI) and may be fed back as CSI feedback parameters along with different channel state information (e.g., PMI, CQI, RI).

In the case of class B operation, different beamforming may be applied for each port within the same resource. In this case, alternatively, only a specific port may be used as a port selection codebook, or a port selection codebook may be combined into a port combination codebook and used.

Further, in enhanced FD-MIMO (eFD-MIMO), a technique called hybrid CSI operation is considered. This is a concept that the existing 2-step process in which the base station transmits CSI-RS and the UE performs CSI calculation and feedback has been extended to a 4-step process in which i) the base station transmits CSI-RS, ii) the UE performs CSI calculation and feedback, iii) the base station transmits CSI-RS based on CSI feedback, and iv) the UE performs CSI calculation and feedback. In this case, the following two mechanisms can be considered.

First, a form of "hybrid CSI mechanism 1" in which the class a operation and the class B operation have been combined may be considered. The corresponding mechanism may be configured such that i) the base station sends non-precoded CSI-RS, ii) the UE feeds back RI and (WB) PMI, iii) the base station sends beamformed CSI-RS based on feedback information, iv) the UE feeds back PMI, RI or CQI of the beamformed CSI-RS.

Next, a "hybrid CSI mechanism 2" may be considered where two class B operations have been combined. The corresponding mechanism may be configured such that i) the base station transmits multiple beamformed CSI-RS resources, ii) the UE feeds back CRI (and hence selects beams), iii) the base station transmits beamformed CSI-RS ports based on CRI, iv) the UE feeds back PMI, RI, or CQI of the CSI-RS.

The PMI/RI described in the present disclosure is not limited to mean PMI/RI in the LTE system, meaning an index value of a precoding matrix (Nt × R matrix) and a rank value of the precoding matrix. Further, the PMI described in the present disclosure means information indicating preferred MIMO precoder information among MIMO precoders applicable in a transmission stage. In this case, the form of the precoder is not limited to a linear precoder that can be expressed as a matrix. Further, the RI described in the present disclosure includes all feedback information indicating the number of preferred transport layers, and can be interpreted in a broader meaning than the RI in LTE.

Such CSI information may be generated for the full system frequency domain, or may be generated for some frequency domains. In particular, in a wideband system, some methods of generating and feeding back CSI information for some preferred frequency domains (e.g., subbands) of individual UEs may be efficient.

Also, in the LTE system, feedback of CSI information is performed through an uplink channel. In general, periodic CSI feedback is performed through a Physical Uplink Control Channel (PUCCH), and aperiodic CSI feedback is performed through a physical uplink control share (PUSCH).

A PUCCH CSI reporting mode for periodic CSI feedback performed through the PUCCH may be defined similarly to table 4. In this case, the PUCCH CSI reporting mode means that it is classified into a mode as to which information the UE must feed back if the UE performs periodic CSI feedback.

[ Table 4]

Unlike periodic CSI feedback, aperiodic CSI feedback is temporarily performed only when the base station requests CSI feedback information. In this case, the base station triggers aperiodic CSI feedback through a downlink control channel such as a Physical Downlink Control Channel (PDCCH)/enhanced PDCCH (epdcch). In an LTE system, if aperiodic CSI feedback is triggered, a PUSCH CSI reporting mode as to which information the UE must feed back may be defined similar to table 5. In this case, the PUSCH CSI reporting mode under which the UE will operate may be indicated by higher layer signaling (i.e., higher layer message).

[ Table 5]

PUCCH has a smaller amount of data (i.e., payload size) than PUSCH, which can be transmitted at one time. In case of PUCCH, it may be difficult to transmit CSI information to be transmitted at one time. Accordingly, a timing (e.g., a subframe) at which the CQI and PMI are transmitted and a timing at which the RI is transmitted may be differently configured according to each PUCCH CSI reporting mode. For example, in case of mode 1-0 of table 4, the UE may transmit RI only at a specific PUCCH transmission timing and may transmit wideband CQI at a different PUCCH transmission timing.

In addition, the PUCCH report type may be defined according to the type of CSI information configured at a specific PUCCH transmission timing. For example, a report type for transmitting only RI corresponds to type 3, and a report type for transmitting only wideband CQI corresponds to type 4. The feedback period and offset value of the RI and the feedback period and offset value of the CQI/PMI may be indicated (or configured) in the UE through higher layer signaling (i.e., higher layer message).

The CSI feedback information is included in Uplink Control Information (UCI).

Reference Signal (RS)

In a wireless communication system, data is transmitted through a wireless channel, and thus a signal may be distorted during transmission. In order for the receiving stage to correctly receive the distorted signal, it is necessary to correct the distortion of the received signal using the channel information. In order to detect channel information, a method of: the channel information is detected using a signal transmission method known to both the transmitting side and the receiving side and the degree of signal distortion when a signal is transmitted through a channel. The above signals are referred to as pilot signals or Reference Signals (RSs).

Further, recently, in most mobile communication systems, a method capable of improving transmission and reception data efficiency by employing a plurality of Tx antennas and a plurality of Rx antennas instead of using one Tx antenna and one Rx antenna when transmitting a packet is used. When transmitting and receiving data using a plurality of I/O antennas, it is necessary to detect a channel state between the Tx antenna and the Rx antenna in order to accurately receive a signal. Therefore, each Tx antenna must have a separate reference signal.

In case of the LTE system, the use of the pilot signal or RS may be defined as 4 types as follows.

(1) And (3) measuring RS: pilot frequency for channel state measurement

1) CSI measurement/reporting usage (short-term measurement): the method is used for the purposes of link adaptation, rank adaptation, closed-loop MIMO precoding and the like.

2) Long-term measurement/reporting usage: for purposes of handover, cell selection/reselection, etc.

(2) And (3) RS demodulation: pilot frequency for physical channel

(3) Positioning RS: pilot for UE position estimation

(4) Multicast-broadcast single frequency network reference signal (MBSFN RS): pilot for multicast/broadcast services

In a mobile communication system, RSs can be basically classified into two types according to their purposes. The RS includes an RS having a channel information acquisition purpose and an RS for data demodulation. The former needs to be transmitted in a wideband because the purpose is to acquire channel information in downlink by the UE. Although the UE does not receive downlink data in a specific subframe, the UE needs to be able to receive and measure a corresponding RS. Further, the RS is used for measurement of handover and the like. The latter is an RS transmitted in a corresponding resource when the base station transmits a downlink. The UE may perform channel estimation by receiving the corresponding RS and may demodulate data. The RS needs to be transmitted in an area where data is transmitted.

In this case, in order to solve the RS overhead problem due to the increase in the number of antennas, a channel state information-RS (CSI-RS) may be used as an RS having a channel information acquisition purpose, and a UE-specific RS may be used as an RS for data demodulation. The CSI-RS is an RS designed only for CSI measurement and feedback, and has very low RS overhead compared to a cell-specific reference signal (CRS). Furthermore, CRS supports up to 4 multiple antenna ports, whereas CSI-RS has been designed to support up to 8 multiple antenna ports.

Also, unlike the CRS, the UE-specific RS is an RS designed only for demodulation of a data channel (i.e., a precoded RS) and its MIMO precoding scheme has been identically applied to a pilot signal at the time of data transmission for a corresponding UE. Therefore, the UE-specific RS only needs to be transmitted by the number of transmission layers (i.e., transmission rank), not by the number of antenna ports as is required for CRS and CSI-RS. Further, the UE-specific RS is characterized as a UE-specific RS because its data channel reception for the corresponding UE is transmitted in the same resource region as the data channel resource region allocated to each UE by the scheduler of the base station.

Also, in case of LTE uplink, a sounding RS (srs) exists as a measurement RS, and for ACK/NACK and CSI feedback, there are a demodulation RS (i.e., DM-RS) for uplink data channel (PUSCH) and a demodulation RS for uplink control channel (PUCCH).

Further, in the case of the NR system, there may be a Phase Tracking Reference Signal (PTRS) for measuring and tracking a change in phase.

CSI framework in NR systems

With regard to MIMO design of NR systems, a CSI framework for measuring and reporting channel states between an eNB and a UE is considered. The CSI framework considered in the NR system is described in detail below.

Unlike the conventional LTE system, which defines the CSI-related process only in the form of a CSI process, the CSI framework may mean to define the CSI-related process using a CSI report setting, a resource setting, and a CSI measurement setting. Accordingly, in the NR system, the CSI-related process can be performed in a more flexible scheme according to channel and/or resource conditions.

That is, the configuration of the CSI-related process in the NR system may be defined by combining the CSI report setting, the resource setting, and the CSI measurement setting.

For example, the UE may be configured to acquire CSI with N ≧ 1CSI report settings, M ≧ 1 resource settings, and one CSI measurement setting. Here, the CSI measurement setting may mean setting information of a link between N CSI report settings and M resource settings. Further, here, the resource setting includes a Reference Signal (RS) setting and/or an interference measurement setting (IM setting).

Fig. 9 shows an example of a CSI framework considered in an NR system to which the method proposed in this specification can be applied.

Reference to fig. 9 may be configured by report settings 902, measurement settings 904, and resource settings 906. Here, the report setting may mean a CSI report setting, the measurement setting may mean a CSI measurement setting, and the resource setting may mean a CSI-RS resource setting.

In fig. 9, CSI-RS resources are illustrated, but the present disclosure is not limited thereto. The CSI-RS resources may be replaced by resources of downlink reference signals (DL RS) that may be used for CSI acquisition or beam management.

As shown in FIG. 9, a report setting 902 may be made up of N (N ≧ 1) report settings (e.g., report setting N1, report setting N2, etc.).

Further, resource setting 906 can be made up of M (M ≧ 1) resource settings (e.g., resource setting M1, resource setting M2, resource setting M3, etc.). Here, each resource setting may include S (S ≧ 1) resource sets, and each resource set may include K (K ≧ 1) CSI-RSs.

Further, the measurement setting 904 may mean setting information indicating a link between the report setting and the resource setting and a measurement type configured for the corresponding link. In this case, each measurement setup may include L (L ≧ 1) links. For example, the measurement setting may include setting information of a link (link l1) between the report setting n1 and the resource setting m1, setting information of a link (link l2) between the report setting n1 and the resource setting m2, and the like.

In this case, each of the link l1 and the link l2 may be configured as either one of a channel measurement link or an interference measurement link. Further, link l1 and/or link l2 may be configured for rate matching or other purposes.

In this case, one or more CSI reporting settings within one CSI measurement setting may be dynamically selected via layer 1(L2) signaling or L2 (layer 2) signaling. Further, the one or more sets of CSI-RS resources selected from the at least one resource setting and the one or more CSI-RS resources selected from the at least one set of CSI-RS resources are also dynamically selected via L1 or L2 signaling.

Hereinafter, CSI report settings, resource settings (i.e., CSI-RS resource settings), and CSI measurement settings constituting a CSI framework considered in the NR system will be described.

CSI report setup

First, the CSI report setting may mean information for setting a type of CSI report to be performed by the UE for the eNB, information included in the CSI report, and the like.

For example, the CSI reporting settings may include a time-domain behavior type of a time domain, a frequency granularity, CSI parameters to be reported (e.g., Precoding Matrix Indicator (PMI), Rank Indicator (RI), and Channel Quality Indicator (CQI)), a CSI type (e.g., CSI type 1 or 2, CSI with high complexity, or CSI with low complexity), a codebook configuration including codebook subset restriction, measurement restriction configuration, and the like.

In the present disclosure, the operation type of the time domain may mean an aperiodic operation, a periodic operation, or a semi-persistent operation.

In this case, the setting parameters of the CSI report setting may be configured (or indicated) through higher layer signaling (e.g., RRC signaling).

Further, with respect to the above CSI reporting setup, wideband reporting, partial band reporting, and subband reporting may be supported as three frequency granularities.

Resource setting

Next, the resource setting may mean information for setting resources to be used for CSI measurement and reporting. For example, the resource settings may include an operation mode of a time domain, a type of RS (e.g., non-zero power CSI-RS (NZP CSI-RS), zero power CSI-RS (ZP CSI-RS), DMRS, etc.), a resource set composed of K resources, and the like.

As described above, each resource setting may include one or more resource sets, and each resource set may include one or more resources (e.g., CSI-RS resources). Further, the resource settings may include settings for signals used for channel measurements and/or interference measurements.

As an example, each resource setting may include setting information for S resource sets (e.g., CSI-RS resource sets), and may also include setting information for K resources of each resource set. In this case, the respective resource sets may correspond to sets differently selected from a pool of all CSI-RS resources configured for the UE. Further, the setting information of each resource may include information of resource elements, the number of ports, the operation type of the time domain, and the like.

Alternatively, as another example, each resource setting may include setting information of S CSI-RS resources and/or K CSI-RS resources numbered equal to or less than a port of each CSI-RS resource.

In this case, the CSI-RS RE mapping pattern of the N-port CSI-RS resource may be configured as one or more CSI-RS mapping patterns of CSI-RS resources having the same or a smaller number of ports (e.g., 2, 4, or 8). In this case, the CSI-RS mapping pattern may be defined within a slot and may span multiple configurable contiguous/non-contiguous OFDM symbols.

In this case, the configuration parameters of the resource setting may be configured through higher layer signaling (e.g., RRC signaling).

Further, in the case of each semi-persistent resource setting or periodic resource setting, periodicity may be additionally included in the configuration information.

CSI measurement setup

Next, the CSI measurement setting may mean setting information indicating which measurement the UE is to perform for a specific CSI report setting and a specific resource setting mapped thereto for CSI reporting. That is, the CSI measurement setting may include information on links between the CSI report setting and the resource setting and may include information indicating a measurement type of each link. Further, the measurement type may mean channel measurement, interference measurement, rate matching, and the like.

As an example, the CSI measurement settings may include information indicating CSI report settings, information indicating resource settings, and settings of a reference transmission scheme in case of CQI. In this regard, the UE may support L ≧ 1CSI measurement setup and the L value may be set according to a capability of the corresponding UE.

In this case, one CSI report setting may be connected to one or more resource settings, and a plurality of CSI report settings may be connected to the same resource setting.

In this case, the setting parameters of the CSI measurement setting may be configured through higher layer signaling (e.g., RRC signaling).

Furthermore, in NR systems, Zero Power (ZP) CSI-RS based interference measurement for CSI feedback is supported. Further, ZP CSI-RS based aperiodic Interference Measurement Resource (IMR), semi-persistent IMR, and periodic IMR for interference measurement for CSI feedback may be supported.

Further, with respect to the CSI report setting, the resource setting, and the CSI measurement setting, the convention of the operation type depending on the time domain is as follows.

First, in case of periodic CSI-RS (i.e., in case of periodically performing transmission of CSI-RS), semi-persistent CSI reporting may be enabled/disabled by MAC CE and/or Downlink Control Information (DCI). In contrast, aperiodic CSI reporting may be triggered by DCI, however, in this case, additional signaling configured to the MAC CE may be required.

Next, in case of semi-persistent CSI-RS (i.e., in case of semi-persistently performing transmission of CSI-RS), periodic CSI reporting is not supported. Instead, semi-persistent CSI reporting may be enabled/disabled by MAC-CE and/or DCI, and semi-persistent CSI-RS may be enabled/disabled by MAC-CE and/or DCI. Also, in this case, aperiodic CSI reporting may be triggered by DCI, and semi-persistent CS-RS may be enabled/disabled by MAC-CE and/or DCI.

Finally, in case of aperiodic CSI-RS (i.e. in case of aperiodic transmission of CSI-RS), periodic (and semi-persistent) CSI reporting is not supported. In contrast, aperiodic CSI reporting may be triggered by DCI, and aperiodic CS-RS may be triggered by DC and/or MAC-CE.

Referring to the above, and convention, in the NR system, three operation types in the time domain may be supported with respect to CSI reporting. In this case, three operation types in the time domain may mean aperiodic CSI reporting, semi-persistent CSI reporting, and periodic CSI reporting. Similarly, with respect to reporting related to (analog and/or digital) beams, NR systems may support some or all of the three types of operation in the time domain.

As described above, aperiodic CSI reporting may mean that the UE performs CSI reporting only when triggered. Further, semi-persistent CSI reporting may mean that the UE performs CSI reporting (according to a certain period) when the corresponding reporting is enabled, and stops CSI reporting when the corresponding reporting is disabled. Further, periodic CSI reporting may mean that the UE performs CSI reporting based on a period and timing (e.g., slot offset) configured through higher layer signaling (e.g., RRC signaling) or the like.

Furthermore, in case of a downlink reference signal (DL RS) for channel measurement at the time of CSI acquisition, three operation types in the time domain (e.g., aperiodic CSI-RS, semi-persistent CSI-RS, and periodic CSI-RS) may be supported. Similarly, some or all of the three types of operation in the time domain may be supported for DL RS for beam management. The CSI-RS is basically regarded as a DL RS for beam management, but another DL signal may be used as a DL RS. For example, the DL RS for beam management may include a mobility RS, a beam RS, a Synchronization Signal (SS), an SS block, a DL DMRS (e.g., PBCH DMRS, PDCCH DMRS), and so on.

As described above, aperiodic CSI-RS may mean that the UE performs measurement on CSI-RS only when triggered. Further, the semi-persistent CSI-RS may mean that the UE performs measurement on the CSI-RS (according to a certain periodicity) when the corresponding CSI-RS is enabled and stops measurement on the CSI-RS when the corresponding CSI-RS is disabled. Further, the periodic CSI-RS may mean that the UE performs measurement on the CSI-RS based on a period and timing (e.g., slot offset) configured through higher layer signaling (e.g., RRC signaling) or the like.

Also, as described above, with respect to an Interference Measurement Resource (IMR) designed in the UE by the base station at the time of CSI acquisition, the NR system may support the ZP CSI-RS based interference measurement method. Also, with respect to an Interference Measurement Resource (IMR), at least one of a non-zero power (NZP) CSI-RS based interference measurement method or a DMRS based interference measurement method may be supported.

In particular, in LTE systems (i.e., legacy LTE systems), the ZP CSI-RS based IMR is configured semi-statically. In contrast, in the NR system, a method of dynamically configuring IMR based on ZP CSI-RS may be supported. For example, aperiodic IMR, semi-persistent IMR, and/or periodic IMR methods based on ZP CSI-RS may be used.

Thus, combinations of various operation types in the time region may be considered for channel estimation (or channel measurement), interference estimation (or interference measurement), and reporting of CSI measurements and reports. For example, the aperiodic CSI report may be configured along with aperiodic/semi-persistent/periodic NZP CSI-RS for channel measurement and aperiodic/semi-persistent/periodic ZP CSI-RS for interference measurement. As another example, a semi-persistent CSI report may be configured along with a semi-persistent/periodic nzp CSI-RS for channel measurements and a semi-persistent/periodic ZP CSI-RS for interference measurements. As another example, the periodic CSI report may be configured along with a periodic NZP CSI-RS for channel measurements and a periodic ZP CSI-RS for interference measurements.

In the present disclosure, "a/B" means a or B, and a combination including an order of change is also considered between "/". For example, "A/B and C/D" may mean "A and C", "A and D", "B and C", or "B and D".

In an example, it is assumed that aperiodic RSs and/or IMRs (e.g., aperiodic NZP CSI-RS and/or aperiodic ZP CSI-RS) are used only for aperiodic reporting, semi-persistent RSs and/or IMRs (e.g., semi-persistent NZP CSI-RS and/or semi-persistent ZP CSI-RS) are used only for aperiodic or semi-persistent reporting, and periodic RSs and/or IMRs (e.g., periodic NZP CSI-RS and/or periodic ZP CSI-RS) are used for all reporting. However, the present disclosure is not so limited and may be configured in various combinations (e.g., semi-persistent reporting configured along with aperiodic RS and/or IMR).

Further, both RS and IMR are included in the resource setting, and whether they are used for the corresponding resources (e.g., for channel estimation or for interference estimation) may be indicated by the configuration of the respective links in the measurement setting.

Further, if the above-described aperiodic CSI reporting is performed in an uplink data channel (e.g., physical uplink control shared (PUSCH)), the following method may be considered.

First, the corresponding CSI report may be configured to be multiplexed with uplink data transmitted through an uplink data channel. In other words, the CSI report and the uplink data may be transmitted together through the uplink data channel.

Alternatively, a configuration may be performed such that the corresponding CSI report is only sent over the uplink data channel, without uplink data.

These methods may be commonly applied to an uplink control channel (e.g., a Physical Uplink Control Channel (PUCCH)) in addition to an uplink data channel.

Multi-antenna structure in NR system

Today, cellular systems evolve to fifth generation (5G) (e.g., NR systems) via fourth generation (4G) (e.g., LTE systems).

In the utilization of 5G communication, in addition to the evolution towards existing smartphone-based mobile broadband services (e.g., eMBB, enhanced mobile broadband), various internet of things (IoT) application services such as healthcare, disaster security, vehicle communication, factory control, and robot control are considered. Accordingly, the form of the UE is variously changed. Further, in 5G communication, it is considered to utilize an ultra high frequency band including a millimeter wave band up to a maximum of 100 GHz.

Since such various implementation forms of UE and ultra high frequency band are used, tens or hundreds of antennas may be regarded as antennas that can be mounted on the UE of the 5G system, unlike the 4G system. For example, as in fig. 10, the vehicle may be one UE, and the plurality of antennas may be distributed and installed at one or more vehicle locations.

Fig. 10 shows an example of a multi-antenna structure to which the method proposed by the present disclosure can be applied.

Alternatively, as another example, as in fig. 11, a plurality of antenna panel arrays may be mounted on the UE in the high frequency band. In this case, the plurality of antenna elements may be distributed at uniform intervals within the antenna panel array, but the antenna orientation or interval may be irregularly configured between the antenna panel arrays.

Fig. 11 shows an example of a plurality of antenna panel arrays to which the method proposed by the present disclosure can be applied.

If multiple antenna arrays and/or panels are installed on the UE with different directivities (or coverage) as in the above example, it may be difficult to apply a codebook designed by assuming a precoding method like uniform linear/matrix array standardization as in the existing Uplink (UL) MIMO method.

Furthermore, if the distances between the plurality of installed antenna arrays and/or panels and the baseband processor are different, a fixed phase difference due to a time delay difference may occur. This may lead to the phenomenon that the time synchronization of the signals transmitted in different antenna elements is different. In the base station reception stage, a phenomenon may occur in which the phase of a signal transmitted in a specific UE antenna group is linearly distorted in proportion to subcarriers (OFDM system, assuming delay difference within CP).

Furthermore, if the signals transmitted in the respective antenna arrays and/or panels use different oscillators, the signals may be transmitted in slightly different frequencies due to errors between the oscillators. This may lead to frequency synchronization errors in the base station. In this case, in the base station, phenomena such as a reduction in the size of a signal transmitted in a specific UE antenna group, phase distortion of the signal, and an increase in noise due to ICI may occur.

Codebook in NR system

In the NR system, a codebook for type 1CSI and a codebook for type 2CSI have been defined.

In case of type 1CSI, a Precoding Matrix Indicator (PMI) codebook may be configured through at least two steps. In this case, the PMI codebook W may be expressed as a product of W1 and W2. In this case, the W1 codebook may mean a codebook used for beam group selection. Further, the W1 codebook means a codebook having a wideband characteristic. The W2 codebook may be used to additionally select the best beam among the beam groups selected through the W1 and to select and compensate the best phase difference value between antenna ports transmitted in two differently polarized antennas belonging to the corresponding beam. The W2 codebook may mean that a codebook having a subband or wideband characteristic is set according to a CSI report.

In case of type 2CSI, the corresponding CSI may be divided into a first category of type 2CSI, a second category of type 2CSI, and a third category of type 2 CSI. In this case, the first category of type 2CSI may mean precoder feedback, the second category of type 2CSI may mean covariance matrix feedback, and the third category of type 2CSI may mean hybrid CSI feedback (e.g., CSI feedback based on port selection/combination codebooks). In this case, even in the case of type 2CSI, the PMI codebook W may be expressed as a product of W1 and W2.

First, in the case of the first category of type 2CSI, W1 may be configured as a set of L orthogonal beams derived from 2-dimensional (2D) DFT beams. In this case, the L-beam set may be configured based on the oversampled 2D DFT beams. Further, beam selection may be performed using broadband characteristics. In contrast, in the case of W2, L beams may be combined in W2 in common with W1. In this case, W2 may mean a subband report or a wideband report used for phase quantization of beam combining coefficients.

Next, in case of the second category of type 2CSI, the feedback of the channel covariance matrix may have long-term and wideband characteristics. In this case, the UE may report a quantized/compressed version of the covariance matrix. The quantization/compression may be based on a set of M orthogonal basis vectors. Further, the corresponding report may include indicators of the M basis vectors and the coefficient set.

Next, in the case of the third category of type 2CSI, a CSI codebook corresponding to the first category of type 2CSI or the second category of type 2CSI may be used along with LTE type B CSI feedback.

The above-described problem of size/phase distortion between UE Tx antenna groups may vary depending on the UE implementation. For example, the above-described wiring problem may be solved in an implementation such that the UE performs a separate procedure of compensating for the delay difference of each antenna group. The oscillator problem can be solved in implementations using a single oscillator or introducing a separate frequency compensation procedure.

However, such compensation processing may increase UE implementation complexity and cost, as it may require separate hardware (e.g., processors and RF circuitry) and so on. As described above, the form of 5G UE (i.e., UE of NR system) includes all UEs that obtain high quality by applying a high cost processor and low cost IoT UE. Therefore, diversity is preferred and a certain level of distortion phenomena is supported.

Therefore, an adaptive uplink multi-antenna transmission scheme according to the magnitude/phase distortion degree of signals between different Antenna Port Groups (APGs) (inter-APG distortion vulnerability level) for each UE and related signaling procedures may be considered like the following methods (methods 1 to 6). Hereinafter, for convenience of description, a distortion vulnerability level (i.e., information that is easily distorted) may be referred to as a DVL in the present disclosure.

Method 1

The UE may report information to the base station as follows.

First, in case of a non-precoded SRS, a UE may report port group information of ports of an uplink Reference Signal (RS) to a base station. In this case, in the SRS port group information, all M SRSs are configured with a plurality of port groups, and the SRS port group information may be information explicitly or implicitly indicating how many SRS ports are included in each port group.

Alternatively, in case of beamformed SRS, the UE may report to the base station the number of uplink antenna arrays/panels/groups, port group information of the reference signals and/or information of the maximum number of reference signal ports per port group of the reference signals. In this case, the base station receiving the information may indicate the port group information in performing uplink reference signal transmission configuration for the corresponding UE.

Further, the UE may additionally report DVL information between port groups to the base station.

In this case, the base station receiving the above-described reference signal port group information may use the corresponding information for one or more of uplink MIMO precoding configuration information, uplink synchronization estimation/correction, uplink channel estimation, or distortion compensation of each Reference Signal (RS) port group. If the correspondence information is used for distortion compensation of each reference signal port group, the base station may signal a size/phase compensation value of each reference signal port group to the UE.

Method 2

The base station may configure the configuration information of the uplink MIMO precoder to be indicated in the UE as follows.

The configuration information of the uplink MIMO precoder may include partial precoder configuration information. Specifically, the configuration information of the uplink MIMO precoder may be configured as PMI information (specifically, in the case of non-precoded SRS) or SRS port index information (specifically, in the case of beamformed SRS) to be used for each SRS port group.

Further, the configuration information of the uplink MIMO precoder may include size/phase concatenation information (e.g., concatenated precoder) between partial precoders. In this case, whether information exists and the size of the information may be different based on the DVL of the UE or the indication of the base station. In addition, whether the concatenated precoder is cycled and the range of the concatenated precoder (e.g., precoder setting information) may also be included in the correspondence information. In addition, the candidate concatenated precoding method may include transmission diversity or open-loop precoding.

Further, the configuration information of the uplink MIMO precoder may include information of the number of simultaneously transmitted data (i.e., rank). This may be indicated as a common value for all SRS ports.

Method 3

Further, with respect to semi-open loop uplink MIMO precoding, a UE having a certain level of DVL or a UE instructed by a base station to use the following scheme may configure a MIMO precoder to be applied at the time of uplink transmission as follows.

The partial precoder may be determined by information (i.e., downlink control information) indicated by the base station.

Further, the concatenated precoder may be randomly selected by the UE in a certain time/frequency resource element, or a predefined concatenated precoder may be configured or defined on higher layer signaling or standards. Alternatively, after generating a plurality of concatenated precoder sets based on concatenated precoder information generated by information (i.e., downlink control information) indicated by the base station, the plurality of concatenated precoder sets may be alternately used in predetermined time/frequency resource elements.

The base station has a plurality of panels, and may transmit data to the UE by multiplying the corresponding panels by different phases. In this case, the magnitude and/or phase distortion level of the signal may vary from panel to panel of the base station depending on the implementation. That is, the DVL value may be defined between downlink antenna ports transmitted in different base station panels, and may be different in each base station. This allows method 2 without any change, and the corresponding content is described based on the corresponding method (i.e., methods 4 to 6).

If the phase values to be applied between the panels are different for each UE, the UE may be configured to feed back the phase optimized for it. In this case, information related to phase feedback of the UE needs to be defined in DCI of an uplink.

Method 4

The base station may inform the UE whether to feed back the phase information through Downlink Control Information (DCI) and/or higher layer signaling (e.g., MAC-CE and/or RRC signaling). In this case, the UE may determine whether to feed back the phase information through downlink control information and/or through higher layer signaling.

Method 5

Furthermore, method 4 can be extended as follows. The base station may determine its own DVL and inform the UE of the DVL. If DVL is set high (i.e., DVL ═ high), the UE may assume that it is not performing feedback of phase information for the base station. In this case, the DVL information may be configured in a cell-specific manner. Further, the DVL information may be transmitted through downlink control information and/or higher layer signaling.

Specifically, the base station may inform the UE of the number of bits to be used in phase information feedback through downlink control information and/or higher layer signaling. The UE may use the number of bits indicated by the base station to determine the level of phase information to be fed back.

In this case, method 5 may be performed after method 4 is performed.

Alternatively, the base station may inform the UE whether to feed back the phase value information between the panels to the base station and the number of bits fed back for the same time. In this case, if feedback is not allowed, the base station may not define a field informing the number of feedback bits. Also, if it is determined that feedback is not allowed, the UE may assume the number of feedback bits to be 0.

Alternatively, regardless of method 4, the base station may inform the UE of the number of feedback bits of phase value information between base station panels. In this case, method 5 may operate independently of method 4. For example, if the feedback bit number of the phase value information between the base station panels is set to 0, the UE may interpret that the corresponding information is not allowed to be fed back.

Method 6

Further, the base station may transmit data (i.e., downlink data) by the following method using the feedback phase information according to the above-described method.

For example, the base station may transmit data while changing and applying a plurality of phase values generated based on phase values between panels fed back in PMIs of the respective panels or phase compensation values fed back by the UE per resource element or resource element group. In this case, the base station may separately transmit demodulation reference signals (DMRS) of the respective panels to the UE so that respective channel estimation of the panels may be performed.

In this case, DMRS ports transmitted in different panels may be configured for transmission of different layers (i.e., independent layer joint transmission) or transmission of the same layer (i.e., same layer joint transmission). Alternatively, only some DMRS ports may correspond to the same layer, and the remaining DMRS ports may be configured for transmission of different layers. In addition, the UE may determine an effective channel by applying a phase after estimating channels of the respective panels.

As another example, the base station may transmit data while changing and applying phase values between panels fed back in PMIs of the respective panels per resource block or resource block group.

In the above method, the panel may be replaced by an antenna array and/or a group of antenna ports. In particular, different base station panels may be extended to different base stations, Transmission Points (TPs) and/or beams.

For example, #0 and #1 among base station panels #0, #1 and #2 may be signals transmitted at TP # a, and #2 may be signals transmitted at TP # B.

In addition, panels belonging to the same TP may be mapped to the same CSI-RS resource and transmit CSI-RS ports to the UE through different antenna port groups. Panels belonging to different TPs may be mapped to different CSI-RS resources.

Alternatively, different CSI-RS resources are mapped to each panel, and whether it is a CSI-RS transmitted in a panel belonging to the same TP or not may be configured by a separate explicit or implicit indicator. For example, whether CSI-RSs are transmitted in different panels and/or beams of the same TP or in different panels/beams of different TPs may be identified according to whether the resources of the QCL are the Same Synchronization Signals (SSBs), Tracking Reference Signals (TRSs), CSI-RSs, or different SSBs, TRSs, or CSI-RSs as the corresponding CSI-RS resources.

If the base station and/or the UE has multiple panels (i.e., multiple antenna panels by the above-described method), a method of compensating for a phase and/or gain difference between panels (according to DVL) and a method of performing DL/UL transmission while the phase and/or gain difference circulates in a specific time and/or frequency resource unit have been proposed.

In the present disclosure, the cycling may mean a precoder cycling in which transmission is performed while changing a precoder in a time/frequency resource unit. For example, performing transmission while a specific precoder circulates in time and/or frequency resource units may mean performing transmission while changing the specific precoder in time and/or frequency resource units.

Hereinafter, the present disclosure proposes a method of configuring and/or indicating a downlink reference signal (e.g., CSI-RS) and/or a method of configuring feedback information related to the downlink reference signal in order to support the above-described operation of the base station.

For convenience of description, a time and/or frequency resource unit in which the base station and/or the UE performs transmission while changing precoding is referred to as a Precoding Resource Group (PRG). For example, if each Physical Resource Block (PRB) performs a cycle, the PRG described above may correspond to 1 PRB on the frequency axis. Alternatively, if N subcarriers are grouped and the precoder circulates, the above PRG may correspond to the N subcarriers.

The methods proposed by the present disclosure may be methods of compensating for and/or combining uncertainties in phase and/or gain differences between multiple panels (i.e., multiple antenna panels). However, the method proposed by the present disclosure may also be equally applied to a case where there is uncertainty in the phase difference and/or the gain difference between different base stations or Transmission Points (TPs).

If the base station has a plurality of panels, the following three methods (hereinafter, methods 1 to 3) may be considered as corresponding PMI feedback codebook configuration methods.

Hereinafter, in the present disclosure, for convenience of description, a matrix for compensating a phase difference and/or a gain difference between panels (i.e., a matrix for compensating phase and/or gain calibration between panels) may be referred to as W₃. In other words, W₃May mean information about how much the phase and/or gain between the panels needs to be compensated. For example, with W₃The relevant matrix index may be referred to as I₃、I_3,1、I_3,2And the like. Alternatively, with W₃Corresponding matrixThe index may be represented as W₁And/or W₂Some matrix indices (e.g., I)_1,4、I_2,4)。

Further, as described above, a matrix for compensating for a phase difference and/or a gain difference between panels having a Wideband (WB) characteristic may be referred to as W₁. The matrix for compensating for phase and/or gain differences between panels having sub-band (SB) characteristics may be referred to as W₂. In this case, for example, with W₁And W₂The relevant matrix index may be referred to as I_1,1、I_1,2、I_2,1、I_2,2And the like.

Method 1

A method of compensating the phase difference and/or the gain difference between the panels as a single value with respect to the full bandwidth may be considered. That is, a configuration may be performed such that a phase difference and/or a gain difference between panels is compensated using a matrix (or codebook) for WB panel compensation. The corresponding method may correspond to a method of configuring a PMI feedback codebook having an attribute of a WB parameter.

In this case, the PMI feedback codebook W may be expressed as W₃W₁W₂And (5) structure.

Method 2

Alternatively, a method of configuring a phase difference and/or a gain difference between each sub-band compensation panel of the full bandwidth may also be considered. That is, a configuration may be performed such that a phase difference and/or a gain difference between panels is compensated using a matrix (or codebook) for SB panel compensation. The corresponding method may correspond to a method of configuring a PMI feedback codebook having an attribute of an SB parameter.

In this case, the PMI feedback codebook W may be expressed as W₁W₂W₃And (5) structure.

Method 3

Alternatively, a method of compensating for a phase difference and/or a gain difference between panels by applying both the method 1 and the method 2 may also be considered. That is, a configuration may be performed such that a phase difference and/or a gain difference between panels is compensated using a matrix (or codebook) for WB panel compensation and a matrix (or codebook) for SB panel compensation. The corresponding method may correspond to a method of configuring a PMI feedback codebook having attributes of WB parameters and SB parameters.

In this case, the PMI feedback codebook W may be expressed as W_3,1W₁W₂W_3,2And (5) structure. In this case, W_3,1Can mean a matrix, W, for compensating the phase difference and/or gain difference of the WB characteristics_3,2May mean a matrix for compensating a phase difference and/or a gain difference of the SB characteristic.

For example, configuration may be performed such that N is being used₁After the bit WB parameters roughly correct (or compensate) the phase difference and/or gain difference, N is used₂The bit SB parameters more accurately correct (or compensate) for the phase difference and/or gain difference.

In this case, the feedback having the SB characteristic may be configured as difference information of the feedback having the WB characteristic.

Hereinafter, a CSI reporting (i.e., CSI feedback) method of the UE according to the CSI reporting mode indication of the base station is described in detail. Specifically, a method of determining a matrix index configuring a Precoding Matrix Indicator (PMI) included in CSI and calculating a Channel Quality Indicator (CQI) based on the above indication of a base station is described.

First embodiment

First, the base station may perform the indication in the UE such that W is correlated in the CSI report of the UE₁And W₂Relative matrix index (e.g., I)_1,1、I_1,2、I_2,1、I_2,2) Is included in the feedback, but is related to W₃Relative matrix index (e.g., I)₃、I_3,1、I_3,2) Excluded from the feedback. For example, such an indication may be referred to as a semi-open loop MIMO based CSI reporting method.

In other words, when the base station configures the CSI reporting mode in the UE, it may be indicated that the UE should not report a matrix (i.e., W) for compensating for a phase difference and/or a gain difference between panels in the PMI to be fed back₃) Is used to determine the index of (1). For example, this may be configured such that it is indicated by a specific CSI reporting mode or CSI reporting parameter.

Such an indication may be configured in the UE by the base station through higher layer signaling (e.g., MAC-CE and/or RRC signaling) and/or physical layer signaling (e.g., DCI).

A UE receiving such an indication may communicate with the W₁And W₂The relevant matrix index is assumed to be the matrix index included in the feedback information, and may be associated with W₃The relevant matrix index value is assumed to be a specific matrix index, and CSI may be calculated. That is, a UE receiving a correspondence indication will not be associated with W₃The relevant matrix index value is reported as feedback information, but the matrix index may be assumed and used as a specific matrix index when calculating CSI.

For example, the UE may report CQI within the CSI, including using the same W₁And W₂Related matrix index and related to W₃The result of the particular matrix index calculation concerned. In other words, a UE receiving a correspondence indication may be configured to respond to a W by calculating a CQI₁And W₂Relative matrix index (e.g., I)_1,1、I_1,2、I_2,1、I_2,2) Assumed to be the index included in the feedback information and to be associated with W₃Relative matrix index (e.g., I)₃、I_3,1、I_3,2) It is assumed that CQI is calculated and reported for one of the following methods (methods 1 to 3 below).

That is, the "and W" used for the above-described CSI calculation (e.g., CQI calculation) can be assumed or determined by one of the following methods₃The relevant specific matrix index ".

Method 1

The UE receiving the indication from the base station can communicate with the W₃The relevant matrix index is assumed to be the index configured and/or indicated by the base station to calculate the CSI. In this case, the base station may configure and/or indicate the matrix index through higher layer signaling (e.g., RRC signaling).

For example, the base station may select and assign a and W₃A particular set (or subset) of matrix indices that are relevant, and the UE may perform CSI computation using the specified matrix indices.

In this case, if the base station is configured and/or indicated for W₃The UE may be configured with the frequency resource list for the corresponding indexThe CSI calculation is performed while changing and applying one matrix index in the bin. Alternatively, in this case, the UE may be based on W calculated for the full band₁And W₂Applying different W₃While the average CSI is calculated.

Method 2

Alternatively, the UE receiving the above indication from the base station may communicate with the W₃The relevant matrix index assumes that the CSI is calculated as a predefined index.

For example, a predefined index may correspond to W₃Lowest matrix index of related matrix indexes (e.g., I)₃The lowest index of). Alternatively, the predefined index may correspond to W₃All matrix indices of interest (e.g., I)₃All indexes of (a).

Method 3

Alternatively, the UE receiving the above indication from the base station may communicate with the W₃The relevant matrix index assumes that the CSI is calculated for its selected index. In this case, the UE may randomly select W₃The associated matrix index.

Furthermore, in the application of the above method, with W₃The information of interest (i.e., phase and/or gain difference information between panels) may be divided into Wideband (WB) information (e.g., W)_3,1) And Subband (SB) information (e.g., W)_3,2) And may be defined or configured. In this case, the UE may report only one of the two pieces of information, and may perform configuration such that a predefined value, a value defined or configured by the base station, or a value randomly selected by the UE is applied to the other. In this case, the base station may configure or indicate which information is to be reported and which information is not to be reported.

For example, the UE may be configured to report W with WB characteristics₃Information, but not feedback of W with SB characteristics₃And (4) information. As another example, the UE may be configured not to feed back W with WB characteristics₃Information, but feeding back W with SB characteristics₃And (4) information.

By comparing a method such as the above with the full open loop MIMO method or the closed loop MIMO method, the UE does not report specific through PMIMatrix index (e.g., and W)₃The relevant matrix index) but assumes and applies the corresponding value when calculating CSI. Accordingly, there is an advantage in that more efficient CSI feedback can be performed.

Second embodiment

In this case, unlike the above-described method of the first embodiment, W is selected at the UE₃After the preference matrix is concerned, it may select a corresponding matrix index within a particular range of phase differences and/or gain differences indicated by the corresponding matrix. Alternatively, selecting W at UE₃The preference matrix concerned may then select the matrix index randomly according to a certain rule or within a certain range of phase and/or gain differences indicated by the corresponding matrix.

Similarly, even in the case of method 1 of the first embodiment described above, if the UE has selected W₃Regarding the preference matrix, the corresponding UE may select a matrix index within the phase difference and/or gain difference indicated by the corresponding matrix and the range configured by the base station (according to a specific rule). Furthermore, even in the case of method 2 of the first embodiment described above, if the UE has selected W₃Regarding the preference matrix, the corresponding UE may select a matrix index (according to a certain rule) within a predefined range and the phase difference and/or gain difference indicated by the corresponding matrix indication.

This is described in detail below.

If the base station indicates, for the UE, report settings corresponding to a method described later (methods 1 to 3 below), the UE may select W₁、W₂And W₃The relevant preference matrices index and include them in the feedback information.

In this case, the UE may assume or determine the "and W" for CSI calculation (e.g., CQI calculation) based on one of the following methods (methods 1 to 3 below)₃The relevant specific matrix index ".

Method 1

W associated with the specific matrix index₃W that can be selected and/or reported by UE₃The phase value and/or gain value indicated in (1), a matrix belonging to a range configured by the base station or havingThe matrix of differences set by the base station is applied together to assume or determine.

Method 2

Alternatively, W is related to the specific matrix index mentioned above₃W that can be selected and/or reported by UE₃The phase values and/or gain values indicated in (a) and the matrix with predefined difference values are applied together for assumption or determination.

Method 3

Alternatively, W is related to the specific matrix index mentioned above₃W selectable and/or reportable by an application UE₃The phase value and/or gain value indicated in (a) and the index selected by the UE. In this case, due to the plurality of W₃Index feedback, overhead may increase. To reduce this feedback overhead, defining a particular index mapping to each W may be considered₃Rules or tables of matrix groups and methods of feeding back corresponding indexes.

Detailed examples of the above method may be as follows.

The base station can be connected with W₁、W₂And W and₃all preference matrix indices that are relevant can be fed back. In this case, the base station receiving the correspondence information is based on the W reported by the UE₃After the value generates a plurality of values, it may indicate that the UE should perform CSI calculation by assuming that the UE transmits the generated values while changing time and/or frequency elements when transmitting data (e.g., DL-SCH).

For example, if the UE reports that the optimal phase difference value between the panels is 30 degrees, the base station may generate values between (30-X) degrees and (30+ X) degrees by considering the DVL between the panels at the time of data transmission, and may apply the values while changing them in time/frequency units.

In this case, the range of the phase difference value between the panels (i.e., X value in the example) or W to be applied by the base station₃The range of matrix indices may be configured by the base station for CSI computation by the UE (e.g., method 1). Alternatively, the range of phase difference values between panels or W to be applied by the base station₃The range of the matrix index may be adjusted or defined to a particular range (e.g., method 2). In additionOptionally, the range of phase difference between the panels or W to be applied by the base station₃The range of matrix indices may be multiple phase difference values or W between UE feedback panels₃The matrix index is applied as an information range at the same time (e.g., method 3).

Third embodiment

In the case of the first and second embodiments described above, it may be assumed that the CSI-RS resource to which the CSI report refers operates based on the CSI-resource setting, a single set of CSI-RS resources within the CSI-RS resource setting, or a single CSI-RS resource. However, the CSI-RS resources, CSI-RS resource sets, and/or CSI-RS resource settings are managed separately for each panel (or antenna panel or antenna array), but the above-described methods of the first and second embodiments may be applied at the time of CSI calculation (e.g., CQI calculation).

In this case, after the base station maps the CSI-RS resources to the UE for each panel (or panel group), it may be indicated that the UE should feed back and W for each CSI-RS resource₁And W₂The associated matrix index. In this case, the base station may instruct the UE to perform CSI computation (e.g., CQI computation) and reporting by assuming ambiguity of phase differences and/or gain differences over multiple resources.

For example, the UE may be configured to select PMIs for each CSI-RS resource (or resource group) for multiple CSI-RS resources (or resource groups) and to feed back the respective PMIs. Specifically, the corresponding UE may select PMIs corresponding to the same Rank Indicator (RI) for the respective CSI-RS resources, and may feed back the respective PMIs and the common RI to the base station.

In this case, in CSI calculation (e.g., CQI calculation) and reporting of the UE, it may be assumed that precoders corresponding to PMIs selected by the UE are applied to antenna ports belonging to respective CSI-RS resources (or resource groups). Furthermore, a concatenated precoder (or a compensating precoder) for phase differences and/or gain differences between antenna port groups belonging to different CSI-RS resources (or resource groups) may be assumed based on one of the following methods (methods 1 to 3 below).

Method 1

A combined precoder for phase differences and/or gain differences between antenna port groups belonging to different CSI-RS resources or resource groups may be assumed to be a precoder corresponding to an index configured and/or indicated by the base station. In this case, the base station may configure and/or indicate the matrix index through higher layer signaling (e.g., RRC signaling) or the like.

Method 2

Alternatively, a combined precoder for phase differences and/or gain differences between antenna port groups belonging to different CSI-RS resources or resource groups may be assumed as a precoder corresponding to a predefined index.

For example, the predefined index may correspond to a lowest matrix index (e.g., a lowest index of the concatenated matrix) among matrix indexes related to the combined precoders. Alternatively, the predefined index may correspond to all matrix indexes related to the combined precoder (e.g., all indexes of the concatenated matrix).

Method 3

Alternatively, a combined precoder for phase differences and/or gain differences between antenna port groups belonging to different CSI-RS resources or resource groups may be assumed as a precoder corresponding to an index selected by the UE.

In the above method, if PMIs selected for respective CSI-RS resources are configured and/or defined to have the same RI, phase differences and/or gain differences may be compensated (or corrected) for respective layers when PMIs are combined.

Alternatively, a method of selecting different RIs may also be applied for each CSI-RS resource. In this case, only some layers may be combined between PMIs, and the remaining layers may not be combined.

Thus, if the UE selects and/or reports respective RIs of respective CSI-RS resources, a group of layers between the CSI-RS resources on which the combining and/or calibration is to be performed and selection and/or reporting information of the UE or indication and/or configuration information of the base station on which the combining and/or calibration is not to be performed may be additionally signaled.

Fourth embodiment

Further, as in the third embodiment described above, if CSI-RS resources, CSI-RS resource sets, and/or CSI-RS resource settings are separately managed, the following exemplary methods can be considered by applying the method of the second embodiment described above.

For example, the UE may be configured to select PMIs for each CSI-RS resource (or resource group) for multiple CSI-RS resources (or resource groups) and to feed back the respective PMIs. Specifically, the corresponding UE may select PMIs corresponding to the same Rank Indicator (RI) for the respective CSI-RS resources and feed back the respective PMIs and the common RI to the base station.

Furthermore, the UE may be configured to select and feed back (with respect to a particular layer) preference indices for concatenated matrices of phase differences and/or gain differences within antenna port groups belonging to different CSI-RS resources (or resource groups) (i.e., combined precoders).

In this case, in CSI calculation (e.g., CQI calculation) and reporting of the UE, it may be assumed that precoders corresponding to PMIs selected by the UE are applied to antenna ports belonging to respective CSI-RS resources (or resource groups). Further, by considering that the concatenated precoder (or the compensating precoder) is changed and applied in time and/or frequency resource units based on one of the following methods (methods 1 to 3 below), a concatenated precoder (or a compensating precoder) for a phase difference and/or a gain difference between antenna port groups belonging to different CSI-RS resources (or resource groups) may be assumed.

Method 1

A combined precoder for phase differences and/or gain differences between antenna port groups belonging to different CSI-RS resources or resource groups may be assumed to be a precoder corresponding to a combined matrix value or index selected and reported by the UE and a value or index belonging to a range configured and/or indicated by the base station. In this case, the UE-selected and reported combination matrix value or index may mean a phase value and/or a gain value indicated in the UE-selected and reported combination matrix. In this case, the base station may configure and/or indicate the range of matrix indexes or the range of phase and/or gain differences through higher layer signaling (e.g., RRC signaling) or the like.

Method 2

Alternatively, the combined precoders for phase differences and/or gain differences between antenna port groups belonging to different CSI-RS resources or resource groups may be assumed to be precoders with different predefined values or indices compared to the combined matrix values or indices selected and reported by the UE. In this case, the UE-selected and reported combination matrix value or index may mean a phase value and/or a gain value indicated in the UE-selected and reported combination matrix.

For example, if the predefined phase difference value is ± 15 degrees, the UE may calculate the CQI by assuming that the base station will vary by (X ± 15) degrees and apply the phase based on the phase difference value X degrees between antenna port groups belonging to different CSI-RS resources (or resource groups) selected and reported.

Method 3

Alternatively, a combined precoder for phase differences and/or gain differences between antenna port groups belonging to different CSI-RS resources or resource groups may be assumed as a precoder corresponding to an index selected by the UE. In this case, the UE may feed back a plurality of values to the base station, or may adjust a feedback index corresponding to a specific range and feed back a corresponding index to the base station.

In the methods 1 to 3 of the first to fourth embodiments described above, if a plurality of matrix indexes are configured, indicated, predefined, or selected, a method of applying each matrix to all bandwidths in which CSI-RSs are transmitted by the UE and then calculating and reporting CSI (e.g., CQI) that can be obtained on average may be considered.

Alternatively, in this case, a method of calculating CSI (e.g., CQI) by the UE by alternately applying matrix indexes configured and/or indicated for respective PRGs (according to a specific rule) with respect to a bandwidth (divided according to a specific rule or divided based on a configuration of the base station) for transmitting CSI-RS may also be considered.

In case of the latter method, the base station may additionally indicate a configuration in the UE regarding which precoder (i.e., which precoding index or matrix index) is to be applied to which PRG set (PRG set) in method 1 or method 2 of various embodiments to calculate CSI.

Fifth embodiment

A multi-panel base station (i.e., a base station with multiple antenna panels) may transmit CSI-RS through separate sets of CSI-RS ports or CSI-RS resources for each panel (or panel group). In this case, if the total number of CSI-RS ports is large, it may be efficient to select some panels (or panel groups) with excellent quality.

For example, a method of selecting some panels or panel groups with superior quality may be more advantageous in terms of system operation and/or PMI feedback accuracy or spatial granularity, based on a limited amount of feedback information. Specifically, if panels belonging to multiple base stations (or TPs) are included in CSI-RS transmission, the UE may be configured to select a base station having excellent quality and perform transmission (i.e., feedback).

Accordingly, a UE configured and/or indicated with N CSI-RS resources may select M CSI-RS resources of the N resources and then apply the above method only to CSI-RS antenna ports belonging to the M resources. In this case, M may be set to be less than or equal to N.

In this case, the base station may additionally indicate or configure configuration information to be assumed when calculating DVL-related information (i.e., distortion-related information) or CSI (e.g., CQI) for each CSI-RS resource group with respect to the UE. In this case, the UE may determine whether to apply the methods described in the above embodiments and which of the methods will be applied based on the DVL status and/or CSI configuration information (e.g., CQI configuration information) of the selected CSI-RS resource group.

For example, if the CSI-RS resource group selected by the UE has severe distortion characteristics between devices (e.g., if DVL is high), the UE may be configured to apply the method described in the first embodiment or the third embodiment. In contrast, if the CSI-RS resource group selected by the UE has normal distortion characteristics between devices (e.g., if DVL ═ is medium), the UE may be configured to apply the method described in the second embodiment or the fourth embodiment. Furthermore, if the CSI-RS resource group selected by the UE has less distortion characteristics between devices (e.g., if DVL is low), the UE may be configured to follow a common closed-loop MIMO-based CSI calculation method, instead of the methods described in the first to fourth embodiments described above. In this case, a common closed-loop MIMO-based CSI calculation method may mean a method of selecting all PMIs by the UE and calculating CQIs if corresponding PMIs have been applied.

Further, in the above example, a method of directly informing which method is to be applied through CSI feedback configuration information of each CSI-RS resource group, instead of DVL, may also be considered.

The UE may be configured to select some CSI-RS resources among the plurality of CSI-RS resources configured and/or indicated for CSI measurement as described above and calculate and report CSI by applying the methods of the first to fourth embodiments described above to the selected CSI-RS resources. In this case, the selected CSI-RS resource may have excellent quality (e.g., a resource with high RSRP, RSRQ, etc.) among the plurality of CSI-RS resources.

That is, although the base station configures a plurality of CSI-RS resources, the UE may autonomously select only some CSI-RS resources and perform CSI measurement. In this case, the index of the CSI-RS resource selected by the UE may be included in the feedback information (i.e., CSI report).

Also, in this case, the base station may additionally configure distortion-related information (i.e., DVL-related information) of the CSI-RS resource group, configuration information of CSI calculation and/or reporting, and the like. Accordingly, the UE may determine whether to apply the first to fourth embodiments described above and which embodiment's method will be applied based on the DVL status of the selected CSI-RS resource group or the configuration related to CQI reporting.

Alternatively, unlike in the above method, the base station may instruct to select M CSI-RS resources for the UE. This may be performed by higher layer signaling (e.g., RRC signaling) and/or lower layer signaling (e.g., DCI).

In other words, the base station may configure N CSI-RS resources for the UE in advance, and may indicate that the UE should dynamically select M of the N CSI-RS resources and perform feedback. For example, the base station may pre-configure the UE with 8 CSI-RS resources through higher layer signaling (e.g., RRC signaling), and may indicate through lower layer signaling (e.g., MAC-CE, DCI) that the UE should select 3 of the 8 CSI-RS resources.

If the method described in the fifth embodiment is used, there is an effect that complexity or overhead related to CSI reporting of the UE may be reduced because CSI measurement may be performed using only some CSI-RS resources satisfying a specific condition (e.g., quality condition) among the configured or indicated CSI-RS resources.

Further, in the above-described embodiments of the present disclosure, if the UE selects rank 2 or more (i.e., if a plurality of layers are selected), the above-described method may be applied to each layer, or may be applied to all layers in common. For example, in the method 1 of the second or fourth embodiment, a method of configuring the range of the phase difference and/or the gain difference of each layer or the range common to all layers by the base station may be applied.

Fig. 12 illustrates an example of an operation flowchart of a UE reporting Channel State Information (CSI) in a wireless communication system to which the method proposed by the present disclosure can be applied. Fig. 12 is for convenience of description only, and does not limit the scope of the present disclosure.

Referring to fig. 12, it is assumed that the UE performs CSI-RS measurement or CSI calculation and reporting based on the methods described in the above-described embodiments of the present disclosure (e.g., the methods of the first and fifth embodiments).

First, the UE may measure CSI-RS transmitted by the base station through multiple panels (step S1205). For example, CSI-RS measurements may be performed on CSI-RS resources configured or indicated by the base station or CSI-RS resources selected by the UE, among CSI-RS resources, as described above.

Thereafter, the UE may report the generated CSI to the base station based on the CSI-RS measurement (step S1210). For example, as described above, the CSI may include PMI, CQI, RI, and the like.

In this case, the base station may configure the UE with a matrix index (e.g., and W) that does not include phase alignment between panels₃In connection with I₃、I_3,1、I_3,2、I_1,4、I_2,4Etc.) of the CSI report. For example, as in the above-described method (the method of the first embodiment), a reporting mode in which a matrix index for phase alignment between panels is not reported as a PMI may be indicated to the UE.

In this case, the CSI reported by the UE may include only the first matrix index (e.g., I) for WB panel compensation_1,1、I_1,2Etc.) and a second matrix index (e.g., I) for SB panel compensation_2,1、I_2,2Etc.). In addition, the method can be used for producing a composite materialThe CSI reported by the UE (e.g., CQI within CSI) may be calculated using the first matrix index, the second matrix index, and a specific matrix index related to phase alignment between panels.

In this case, the first matrix index and/or the second matrix index may be included in a PMI within CSI and reported. Further, the result of calculation using the first matrix index, the second matrix index, and a specific matrix index related to phase alignment between panels may be included in CQI within CSI and reported.

For example, as in the above-described method, the specific matrix index may be indicated by the base station through higher layer signaling or may belong to a matrix index set configured by the base station through higher layer signaling. Alternatively, the specific matrix index may correspond to the lowest matrix index among matrix indexes pre-configured with respect to phase calibration between panels, or may correspond to all matrix indexes pre-configured with respect to phase calibration between panels. Alternatively, the specific matrix index may correspond to a matrix index randomly selected by the UE among matrix indexes related to phase alignment between panels.

Overview of devices to which the present disclosure may be applied

Fig. 13 shows a block diagram of a wireless communication device according to an embodiment of the present disclosure.

Referring to fig. 13, the wireless communication system includes a base station (or network) 1310 and a UE 1320.

Base station 1310 includes a processor 1311, memory 1312, and a communication module 1313.

The processor 1311 implements the functions, processes, and/or methods set forth in fig. 1-12. Layers of a radio interface protocol may be implemented by the processor 1311. The memory 1312 is connected to the processor 1311 and stores various information for driving the processor 1311. The communication module 1313 is connected to the processor 1311 and transmits and/or receives a radio signal.

The communication module 1313 may include a Radio Frequency (RF) unit for transmitting and receiving a radio signal.

The UE 1320 includes a processor 1321, a memory 1322, and a communication module (or RF unit) 1323. The processor 1321 implements the functions, processes, and/or methods set forth in fig. 1-12. Layers of the radio interface protocol may be implemented by the processor 1321. The memory 1322 is connected to the processor 1321 and stores various information for driving the processor 1321. The communication module 1323 is connected to the processor 1321 and transmits and/or receives a radio signal.

The memory 1312, 1322 may be internal or external to the processor 1311, 1321 and may be connected to the processor 1311, 1321 by various well-known means.

Further, base station 1310 and/or UE 1320 may have a single antenna or multiple antennas.

Fig. 14 shows a block diagram of a communication device according to an embodiment of the present disclosure.

Specifically, fig. 14 is a diagram more specifically illustrating the UE of fig. 13.

Referring to fig. 14, the UE may include a processor (or Digital Signal Processor (DSP))1410, an RF module (or RF unit) 1435, a power management module 1405, an antenna 1440, a battery 1455, a display 1415, a keypad 1420, memory 1430, a Subscriber Identity Module (SIM) card 1425 (this element is optional), a speaker 1445, and a microphone 1450. Further, the UE may include a single antenna or multiple antennas.

The processor 1410 implements the functions, processes, and/or methods set forth in fig. 1-12. Layers of a radio interface protocol may be implemented by the processor 1410.

The memory 1430 is connected to the processor 1410 and stores information related to the operation of the processor 1410. The memory 1430 may be located inside or outside the processor 1410 and may be connected to the processor 1410 by various well-known means.

For example, the user inputs command information such as a phone number by pressing (or touching) buttons of the keypad 1420 or by voice activation using the microphone 1450. Processor 1410 receives such command information and performs processing so that appropriate functions, such as dialing a telephone number, are performed. Operational data may be retrieved from the SIM card 1425 or the memory 1430. Further, the processor 1410 may display command information or driving information on the display 1415 for user identification or convenience.

The RF module 1435 is connected to the processor 1410 and transmits and/or receives an RF signal. For example, the processor 1410 transfers command information to the RF module 1435 to cause the RF module 1435 to transmit a radio signal forming voice communication data in order to initiate communication. The RF module 1435 includes a receiver and a transmitter to receive and transmit radio signals. The antenna 1440 is used for transmitting and receiving radio signals. Upon receiving the radio signal, the RF module 1435 transmits the radio signal so that it is processed by the processor 1410 and can convert the signal to a baseband. The processed signals may be converted into audible or readable information that is output through speaker 1445.

The above embodiments are achieved by a combination of structural elements and features of the present disclosure in a predetermined manner. Unless individually specified, each structural element or feature should be selectively considered. Each structural element or feature may be implemented without being combined with other structural elements or features. In addition, some structural elements and/or features may be combined with each other to constitute the embodiments of the present disclosure. The order of operations described in the embodiments of the present disclosure may be changed. Some structural elements or features of one embodiment may be included in another embodiment or may be replaced by corresponding structural elements or features of another embodiment. Further, it is apparent that some claims referring to specific claims may be combined with another claims referring to other claims other than the specific claims to constitute the embodiment, or new claims may be added by modification after filing the application.

Embodiments of the present disclosure may be implemented by various means, such as hardware, firmware, software, or a combination thereof. In an implementation by hardware, the method according to an embodiment of the present disclosure may be implemented by one or more Application Specific Integrated Circuits (ASICs), Digital Signal Processors (DSPs), Digital Signal Processing Devices (DSPDs), Programmable Logic Devices (PLDs), Field Programmable Gate Arrays (FPGAs), processors, controllers, micro-controllers, microprocessors, and the like.

In the case of implementation by firmware or software, the embodiments of the present disclosure may be implemented in the form of modules, procedures, functions, and the like. The software codes may be stored in a memory and executed by a processor. The memory may be located inside or outside the processor, and may transmit and receive data to and from the processor via various known means.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present disclosure without departing from the spirit or scope of the disclosure. Thus, it is intended that the present disclosure cover the modifications and variations of this disclosure provided they come within the scope of the appended claims and their equivalents.

Industrial applicability

Although the method of transmitting and receiving an uplink channel in a wireless communication system of the present disclosure is described based on an example in which the method is applied to a 3GPP LTE/LTE-a system and 5G, it is applicable to various wireless communication systems in addition to the 3GPP LTE/LTE-a system and 5G.

Claims (13)

1. A method of reporting channel state information, CSI, by a user equipment in a wireless communication system, the method comprising the steps of:

measuring CSI-reference signal RS transmitted from the base station through the multi-panel, and

reporting the CSI generated based on the CSI-RS measurement to the base station,

wherein if a CSI report not including a matrix index for phase alignment between panels is configured for the user equipment from the base station, the CSI includes only a first matrix index for wideband WB panel compensation and a second matrix index for subband SB panel compensation, and the CSI is calculated using the first matrix index, the second matrix index, and a specific matrix index related to the phase alignment between panels.

2. The method of claim 1, wherein the first and second light sources are selected from the group consisting of,

wherein the first matrix index and the second matrix index are included in a Precoding Matrix Indicator (PMI) within the CSI and reported.

3. The method of claim 2, wherein the first and second light sources are selected from the group consisting of,

wherein a result of the specific matrix index calculation related to the phase alignment between panels, using the first matrix index, the second matrix index, and the first matrix index is included in a Channel Quality Indicator (CQI) within the CSI and reported.

4. The method of claim 3, wherein the first and second light sources are selected from the group consisting of,

wherein the specific matrix index is indicated by the base station through higher layer signaling.

5. The method of claim 3, wherein the first and second light sources are selected from the group consisting of,

wherein the specific matrix index belongs to a matrix index set configured by the base station through higher layer signaling.

6. The method of claim 3, wherein the first and second light sources are selected from the group consisting of,

wherein the specific matrix index corresponds to a lowest matrix index among matrix indexes pre-configured with respect to the phase alignment between panels.

7. The method of claim 3, wherein the first and second light sources are selected from the group consisting of,

wherein the particular matrix index corresponds to all matrix indexes pre-configured with respect to the phase alignment between panels.

8. The method of claim 3, wherein the first and second light sources are selected from the group consisting of,

wherein the specific matrix index corresponds to a matrix index randomly selected by the user equipment among matrix indexes related to the phase alignment between panels.

9. The method of claim 3, wherein the first and second light sources are selected from the group consisting of,

wherein CSI-RS measurement is performed on at least one CSI-RS resource selected by the user equipment among CSI-RS resources configured by the base station.

10. The method of claim 9, wherein the first and second light sources are selected from the group consisting of,

wherein the CSI further comprises an index of the at least one CSI-RS resource.

11. A user equipment reporting channel state information, CSI, in a wireless communication system, the user equipment comprising:

a Radio Frequency (RF) unit for transmitting and receiving a wireless signal; and

a processor controlling the RF unit,

wherein the processor is configured to:

measuring CSI-reference signal RS transmitted from the base station through the multi-panel, and

reporting the CSI generated based on the CSI-RS measurement to the base station,

wherein if a CSI report not including a matrix index for phase alignment between panels is configured for the user equipment from the base station, the CSI includes only a first matrix index for wideband WB panel compensation and a second matrix index for subband SB panel compensation, and the CSI is calculated using the first matrix index, the second matrix index, and a specific matrix index related to the phase alignment between panels.

12. The user equipment according to claim 11, wherein,

wherein the first matrix index and the second matrix index are included in a Precoding Matrix Indicator (PMI) within the CSI and reported.

13. The user equipment according to claim 12, wherein the user equipment,

wherein a result of the specific matrix index calculation related to the phase alignment between panels, using the first matrix index, the second matrix index, and the first matrix index is included in a Channel Quality Indicator (CQI) within the CSI and reported.

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